diff options
Diffstat (limited to 'Documentation')
39 files changed, 513 insertions, 207 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 9605dbd4b5b5..5eea46fefcb2 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -511,10 +511,12 @@ Description: Control Symetric Multi Threading (SMT) control: Read/write interface to control SMT. Possible values: - "on" SMT is enabled - "off" SMT is disabled - "forceoff" SMT is force disabled. Cannot be changed. - "notsupported" SMT is not supported by the CPU + "on" SMT is enabled + "off" SMT is disabled + "forceoff" SMT is force disabled. Cannot be changed. + "notsupported" SMT is not supported by the CPU + "notimplemented" SMT runtime toggling is not + implemented for the architecture If control status is "forceoff" or "notsupported" writes are rejected. diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index 18f179807563..c30c1957c7e6 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -155,8 +155,7 @@ keeping lock contention under control at all tree levels regardless of the level of loading on the system. </p><p>RCU updaters wait for normal grace periods by registering -RCU callbacks, either directly via <tt>call_rcu()</tt> and -friends (namely <tt>call_rcu_bh()</tt> and <tt>call_rcu_sched()</tt>), +RCU callbacks, either directly via <tt>call_rcu()</tt> or indirectly via <tt>synchronize_rcu()</tt> and friends. RCU callbacks are represented by <tt>rcu_head</tt> structures, which are queued on <tt>rcu_data</tt> structures while they are diff --git a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html index 19e7a5fb6b73..57300db4b5ff 100644 --- a/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html +++ b/Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.html @@ -56,6 +56,7 @@ sections. RCU-preempt Expedited Grace Periods</a></h2> <p> +<tt>CONFIG_PREEMPT=y</tt> kernels implement RCU-preempt. The overall flow of the handling of a given CPU by an RCU-preempt expedited grace period is shown in the following diagram: @@ -139,6 +140,7 @@ or offline, among other things. RCU-sched Expedited Grace Periods</a></h2> <p> +<tt>CONFIG_PREEMPT=n</tt> kernels implement RCU-sched. The overall flow of the handling of a given CPU by an RCU-sched expedited grace period is shown in the following diagram: @@ -146,7 +148,7 @@ expedited grace period is shown in the following diagram: <p> As with RCU-preempt, RCU-sched's -<tt>synchronize_sched_expedited()</tt> ignores offline and +<tt>synchronize_rcu_expedited()</tt> ignores offline and idle CPUs, again because they are in remotely detectable quiescent states. However, because the diff --git a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html index 8d21af02b1f0..c64f8d26609f 100644 --- a/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html +++ b/Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html @@ -34,12 +34,11 @@ Similarly, any code that happens before the beginning of a given RCU grace period is guaranteed to see the effects of all accesses following the end of that grace period that are within RCU read-side critical sections. -<p>This guarantee is particularly pervasive for <tt>synchronize_sched()</tt>, -for which RCU-sched read-side critical sections include any region +<p>Note well that RCU-sched read-side critical sections include any region of code for which preemption is disabled. Given that each individual machine instruction can be thought of as an extremely small region of preemption-disabled code, one can think of -<tt>synchronize_sched()</tt> as <tt>smp_mb()</tt> on steroids. +<tt>synchronize_rcu()</tt> as <tt>smp_mb()</tt> on steroids. <p>RCU updaters use this guarantee by splitting their updates into two phases, one of which is executed before the grace period and diff --git a/Documentation/RCU/NMI-RCU.txt b/Documentation/RCU/NMI-RCU.txt index 687777f83b23..881353fd5bff 100644 --- a/Documentation/RCU/NMI-RCU.txt +++ b/Documentation/RCU/NMI-RCU.txt @@ -81,18 +81,19 @@ currently executing on some other CPU. We therefore cannot free up any data structures used by the old NMI handler until execution of it completes on all other CPUs. -One way to accomplish this is via synchronize_sched(), perhaps as +One way to accomplish this is via synchronize_rcu(), perhaps as follows: unset_nmi_callback(); - synchronize_sched(); + synchronize_rcu(); kfree(my_nmi_data); -This works because synchronize_sched() blocks until all CPUs complete -any preemption-disabled segments of code that they were executing. -Since NMI handlers disable preemption, synchronize_sched() is guaranteed +This works because (as of v4.20) synchronize_rcu() blocks until all +CPUs complete any preemption-disabled segments of code that they were +executing. +Since NMI handlers disable preemption, synchronize_rcu() is guaranteed not to return until all ongoing NMI handlers exit. It is therefore safe -to free up the handler's data as soon as synchronize_sched() returns. +to free up the handler's data as soon as synchronize_rcu() returns. Important note: for this to work, the architecture in question must invoke nmi_enter() and nmi_exit() on NMI entry and exit, respectively. diff --git a/Documentation/RCU/UP.txt b/Documentation/RCU/UP.txt index 90ec5341ee98..53bde717017b 100644 --- a/Documentation/RCU/UP.txt +++ b/Documentation/RCU/UP.txt @@ -86,10 +86,8 @@ even on a UP system. So do not do it! Even on a UP system, the RCU infrastructure -must- respect grace periods, and -must- invoke callbacks from a known environment in which no locks are held. -It -is- safe for synchronize_sched() and synchronize_rcu_bh() to return -immediately on an UP system. It is also safe for synchronize_rcu() -to return immediately on UP systems, except when running preemptable -RCU. +Note that it -is- safe for synchronize_rcu() to return immediately on +UP systems, including !PREEMPT SMP builds running on UP systems. Quick Quiz #3: Why can't synchronize_rcu() return immediately on UP systems running preemptable RCU? diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 6f469864d9f5..e98ff261a438 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -182,16 +182,13 @@ over a rather long period of time, but improvements are always welcome! when publicizing a pointer to a structure that can be traversed by an RCU read-side critical section. -5. If call_rcu(), or a related primitive such as call_rcu_bh(), - call_rcu_sched(), or call_srcu() is used, the callback function - will be called from softirq context. In particular, it cannot - block. +5. If call_rcu() or call_srcu() is used, the callback function will + be called from softirq context. In particular, it cannot block. -6. Since synchronize_rcu() can block, it cannot be called from - any sort of irq context. The same rule applies for - synchronize_rcu_bh(), synchronize_sched(), synchronize_srcu(), - synchronize_rcu_expedited(), synchronize_rcu_bh_expedited(), - synchronize_sched_expedite(), and synchronize_srcu_expedited(). +6. Since synchronize_rcu() can block, it cannot be called + from any sort of irq context. The same rule applies + for synchronize_srcu(), synchronize_rcu_expedited(), and + synchronize_srcu_expedited(). The expedited forms of these primitives have the same semantics as the non-expedited forms, but expediting is both expensive and @@ -212,20 +209,20 @@ over a rather long period of time, but improvements are always welcome! of the system, especially to real-time workloads running on the rest of the system. -7. If the updater uses call_rcu() or synchronize_rcu(), then the - corresponding readers must use rcu_read_lock() and - rcu_read_unlock(). If the updater uses call_rcu_bh() or - synchronize_rcu_bh(), then the corresponding readers must - use rcu_read_lock_bh() and rcu_read_unlock_bh(). If the - updater uses call_rcu_sched() or synchronize_sched(), then - the corresponding readers must disable preemption, possibly - by calling rcu_read_lock_sched() and rcu_read_unlock_sched(). - If the updater uses synchronize_srcu() or call_srcu(), then - the corresponding readers must use srcu_read_lock() and +7. As of v4.20, a given kernel implements only one RCU flavor, + which is RCU-sched for PREEMPT=n and RCU-preempt for PREEMPT=y. + If the updater uses call_rcu() or synchronize_rcu(), + then the corresponding readers my use rcu_read_lock() and + rcu_read_unlock(), rcu_read_lock_bh() and rcu_read_unlock_bh(), + or any pair of primitives that disables and re-enables preemption, + for example, rcu_read_lock_sched() and rcu_read_unlock_sched(). + If the updater uses synchronize_srcu() or call_srcu(), + then the corresponding readers must use srcu_read_lock() and srcu_read_unlock(), and with the same srcu_struct. The rules for the expedited primitives are the same as for their non-expedited counterparts. Mixing things up will result in confusion and - broken kernels. + broken kernels, and has even resulted in an exploitable security + issue. One exception to this rule: rcu_read_lock() and rcu_read_unlock() may be substituted for rcu_read_lock_bh() and rcu_read_unlock_bh() @@ -288,8 +285,7 @@ over a rather long period of time, but improvements are always welcome! d. Periodically invoke synchronize_rcu(), permitting a limited number of updates per grace period. - The same cautions apply to call_rcu_bh(), call_rcu_sched(), - call_srcu(), and kfree_rcu(). + The same cautions apply to call_srcu() and kfree_rcu(). Note that although these primitives do take action to avoid memory exhaustion when any given CPU has too many callbacks, a determined @@ -322,7 +318,7 @@ over a rather long period of time, but improvements are always welcome! 11. Any lock acquired by an RCU callback must be acquired elsewhere with softirq disabled, e.g., via spin_lock_irqsave(), - spin_lock_bh(), etc. Failing to disable irq on a given + spin_lock_bh(), etc. Failing to disable softirq on a given acquisition of that lock will result in deadlock as soon as the RCU softirq handler happens to run your RCU callback while interrupting that acquisition's critical section. @@ -335,13 +331,16 @@ over a rather long period of time, but improvements are always welcome! must use whatever locking or other synchronization is required to safely access and/or modify that data structure. - RCU callbacks are -usually- executed on the same CPU that executed - the corresponding call_rcu(), call_rcu_bh(), or call_rcu_sched(), - but are by -no- means guaranteed to be. For example, if a given - CPU goes offline while having an RCU callback pending, then that - RCU callback will execute on some surviving CPU. (If this was - not the case, a self-spawning RCU callback would prevent the - victim CPU from ever going offline.) + Do not assume that RCU callbacks will be executed on the same + CPU that executed the corresponding call_rcu() or call_srcu(). + For example, if a given CPU goes offline while having an RCU + callback pending, then that RCU callback will execute on some + surviving CPU. (If this was not the case, a self-spawning RCU + callback would prevent the victim CPU from ever going offline.) + Furthermore, CPUs designated by rcu_nocbs= might well -always- + have their RCU callbacks executed on some other CPUs, in fact, + for some real-time workloads, this is the whole point of using + the rcu_nocbs= kernel boot parameter. 13. Unlike other forms of RCU, it -is- permissible to block in an SRCU read-side critical section (demarked by srcu_read_lock() @@ -381,11 +380,11 @@ over a rather long period of time, but improvements are always welcome! SRCU's expedited primitive (synchronize_srcu_expedited()) never sends IPIs to other CPUs, so it is easier on - real-time workloads than is synchronize_rcu_expedited(), - synchronize_rcu_bh_expedited() or synchronize_sched_expedited(). + real-time workloads than is synchronize_rcu_expedited(). - Note that rcu_dereference() and rcu_assign_pointer() relate to - SRCU just as they do to other forms of RCU. + Note that rcu_assign_pointer() relates to SRCU just as it does to + other forms of RCU, but instead of rcu_dereference() you should + use srcu_dereference() in order to avoid lockdep splats. 14. The whole point of call_rcu(), synchronize_rcu(), and friends is to wait until all pre-existing readers have finished before @@ -405,6 +404,9 @@ over a rather long period of time, but improvements are always welcome! read-side critical sections. It is the responsibility of the RCU update-side primitives to deal with this. + For SRCU readers, you can use smp_mb__after_srcu_read_unlock() + immediately after an srcu_read_unlock() to get a full barrier. + 16. Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the __rcu sparse checks to validate your RCU code. These can help find problems as follows: @@ -428,22 +430,19 @@ over a rather long period of time, but improvements are always welcome! These debugging aids can help you find problems that are otherwise extremely difficult to spot. -17. If you register a callback using call_rcu(), call_rcu_bh(), - call_rcu_sched(), or call_srcu(), and pass in a function defined - within a loadable module, then it in necessary to wait for - all pending callbacks to be invoked after the last invocation - and before unloading that module. Note that it is absolutely - -not- sufficient to wait for a grace period! The current (say) - synchronize_rcu() implementation waits only for all previous - callbacks registered on the CPU that synchronize_rcu() is running - on, but it is -not- guaranteed to wait for callbacks registered - on other CPUs. +17. If you register a callback using call_rcu() or call_srcu(), and + pass in a function defined within a loadable module, then it in + necessary to wait for all pending callbacks to be invoked after + the last invocation and before unloading that module. Note that + it is absolutely -not- sufficient to wait for a grace period! + The current (say) synchronize_rcu() implementation is -not- + guaranteed to wait for callbacks registered on other CPUs. + Or even on the current CPU if that CPU recently went offline + and came back online. You instead need to use one of the barrier functions: o call_rcu() -> rcu_barrier() - o call_rcu_bh() -> rcu_barrier() - o call_rcu_sched() -> rcu_barrier() o call_srcu() -> srcu_barrier() However, these barrier functions are absolutely -not- guaranteed diff --git a/Documentation/RCU/rcu.txt b/Documentation/RCU/rcu.txt index 721b3e426515..c818cf65c5a9 100644 --- a/Documentation/RCU/rcu.txt +++ b/Documentation/RCU/rcu.txt @@ -52,10 +52,10 @@ o If I am running on a uniprocessor kernel, which can only do one o How can I see where RCU is currently used in the Linux kernel? Search for "rcu_read_lock", "rcu_read_unlock", "call_rcu", - "rcu_read_lock_bh", "rcu_read_unlock_bh", "call_rcu_bh", - "srcu_read_lock", "srcu_read_unlock", "synchronize_rcu", - "synchronize_net", "synchronize_srcu", and the other RCU - primitives. Or grab one of the cscope databases from: + "rcu_read_lock_bh", "rcu_read_unlock_bh", "srcu_read_lock", + "srcu_read_unlock", "synchronize_rcu", "synchronize_net", + "synchronize_srcu", and the other RCU primitives. Or grab one + of the cscope databases from: http://www.rdrop.com/users/paulmck/RCU/linuxusage/rculocktab.html diff --git a/Documentation/RCU/rcu_dereference.txt b/Documentation/RCU/rcu_dereference.txt index ab96227bad42..bf699e8cfc75 100644 --- a/Documentation/RCU/rcu_dereference.txt +++ b/Documentation/RCU/rcu_dereference.txt @@ -351,3 +351,106 @@ garbage values. In short, rcu_dereference() is -not- optional when you are going to dereference the resulting pointer. + + +WHICH MEMBER OF THE rcu_dereference() FAMILY SHOULD YOU USE? + +First, please avoid using rcu_dereference_raw() and also please avoid +using rcu_dereference_check() and rcu_dereference_protected() with a +second argument with a constant value of 1 (or true, for that matter). +With that caution out of the way, here is some guidance for which +member of the rcu_dereference() to use in various situations: + +1. If the access needs to be within an RCU read-side critical + section, use rcu_dereference(). With the new consolidated + RCU flavors, an RCU read-side critical section is entered + using rcu_read_lock(), anything that disables bottom halves, + anything that disables interrupts, or anything that disables + preemption. + +2. If the access might be within an RCU read-side critical section + on the one hand, or protected by (say) my_lock on the other, + use rcu_dereference_check(), for example: + + p1 = rcu_dereference_check(p->rcu_protected_pointer, + lockdep_is_held(&my_lock)); + + +3. If the access might be within an RCU read-side critical section + on the one hand, or protected by either my_lock or your_lock on + the other, again use rcu_dereference_check(), for example: + + p1 = rcu_dereference_check(p->rcu_protected_pointer, + lockdep_is_held(&my_lock) || + lockdep_is_held(&your_lock)); + +4. If the access is on the update side, so that it is always protected + by my_lock, use rcu_dereference_protected(): + + p1 = rcu_dereference_protected(p->rcu_protected_pointer, + lockdep_is_held(&my_lock)); + + This can be extended to handle multiple locks as in #3 above, + and both can be extended to check other conditions as well. + +5. If the protection is supplied by the caller, and is thus unknown + to this code, that is the rare case when rcu_dereference_raw() + is appropriate. In addition, rcu_dereference_raw() might be + appropriate when the lockdep expression would be excessively + complex, except that a better approach in that case might be to + take a long hard look at your synchronization design. Still, + there are data-locking cases where any one of a very large number + of locks or reference counters suffices to protect the pointer, + so rcu_dereference_raw() does have its place. + + However, its place is probably quite a bit smaller than one + might expect given the number of uses in the current kernel. + Ditto for its synonym, rcu_dereference_check( ... , 1), and + its close relative, rcu_dereference_protected(... , 1). + + +SPARSE CHECKING OF RCU-PROTECTED POINTERS + +The sparse static-analysis tool checks for direct access to RCU-protected +pointers, which can result in "interesting" bugs due to compiler +optimizations involving invented loads and perhaps also load tearing. +For example, suppose someone mistakenly does something like this: + + p = q->rcu_protected_pointer; + do_something_with(p->a); + do_something_else_with(p->b); + +If register pressure is high, the compiler might optimize "p" out +of existence, transforming the code to something like this: + + do_something_with(q->rcu_protected_pointer->a); + do_something_else_with(q->rcu_protected_pointer->b); + +This could fatally disappoint your code if q->rcu_protected_pointer +changed in the meantime. Nor is this a theoretical problem: Exactly +this sort of bug cost Paul E. McKenney (and several of his innocent +colleagues) a three-day weekend back in the early 1990s. + +Load tearing could of course result in dereferencing a mashup of a pair +of pointers, which also might fatally disappoint your code. + +These problems could have been avoided simply by making the code instead +read as follows: + + p = rcu_dereference(q->rcu_protected_pointer); + do_something_with(p->a); + do_something_else_with(p->b); + +Unfortunately, these sorts of bugs can be extremely hard to spot during +review. This is where the sparse tool comes into play, along with the +"__rcu" marker. If you mark a pointer declaration, whether in a structure +or as a formal parameter, with "__rcu", which tells sparse to complain if +this pointer is accessed directly. It will also cause sparse to complain +if a pointer not marked with "__rcu" is accessed using rcu_dereference() +and friends. For example, ->rcu_protected_pointer might be declared as +follows: + + struct foo __rcu *rcu_protected_pointer; + +Use of "__rcu" is opt-in. If you choose not to use it, then you should +ignore the sparse warnings. diff --git a/Documentation/RCU/rcubarrier.txt b/Documentation/RCU/rcubarrier.txt index 5d7759071a3e..a2782df69732 100644 --- a/Documentation/RCU/rcubarrier.txt +++ b/Documentation/RCU/rcubarrier.txt @@ -83,16 +83,15 @@ Pseudo-code using rcu_barrier() is as follows: 2. Execute rcu_barrier(). 3. Allow the module to be unloaded. -There are also rcu_barrier_bh(), rcu_barrier_sched(), and srcu_barrier() -functions for the other flavors of RCU, and you of course must match -the flavor of rcu_barrier() with that of call_rcu(). If your module -uses multiple flavors of call_rcu(), then it must also use multiple +There is also an srcu_barrier() function for SRCU, and you of course +must match the flavor of rcu_barrier() with that of call_rcu(). If your +module uses multiple flavors of call_rcu(), then it must also use multiple flavors of rcu_barrier() when unloading that module. For example, if -it uses call_rcu_bh(), call_srcu() on srcu_struct_1, and call_srcu() on +it uses call_rcu(), call_srcu() on srcu_struct_1, and call_srcu() on srcu_struct_2(), then the following three lines of code will be required when unloading: - 1 rcu_barrier_bh(); + 1 rcu_barrier(); 2 srcu_barrier(&srcu_struct_1); 3 srcu_barrier(&srcu_struct_2); @@ -185,12 +184,12 @@ module invokes call_rcu() from timers, you will need to first cancel all the timers, and only then invoke rcu_barrier() to wait for any remaining RCU callbacks to complete. -Of course, if you module uses call_rcu_bh(), you will need to invoke -rcu_barrier_bh() before unloading. Similarly, if your module uses -call_rcu_sched(), you will need to invoke rcu_barrier_sched() before -unloading. If your module uses call_rcu(), call_rcu_bh(), -and- -call_rcu_sched(), then you will need to invoke each of rcu_barrier(), -rcu_barrier_bh(), and rcu_barrier_sched(). +Of course, if you module uses call_rcu(), you will need to invoke +rcu_barrier() before unloading. Similarly, if your module uses +call_srcu(), you will need to invoke srcu_barrier() before unloading, +and on the same srcu_struct structure. If your module uses call_rcu() +-and- call_srcu(), then you will need to invoke rcu_barrier() -and- +srcu_barrier(). Implementing rcu_barrier() @@ -223,8 +222,8 @@ shown below. Note that the final "1" in on_each_cpu()'s argument list ensures that all the calls to rcu_barrier_func() will have completed before on_each_cpu() returns. Line 9 then waits for the completion. -This code was rewritten in 2008 to support rcu_barrier_bh() and -rcu_barrier_sched() in addition to the original rcu_barrier(). +This code was rewritten in 2008 and several times thereafter, but this +still gives the general idea. The rcu_barrier_func() runs on each CPU, where it invokes call_rcu() to post an RCU callback, as follows: diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 1ace20815bb1..981651a8b65d 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -310,7 +310,7 @@ reader, updater, and reclaimer. rcu_assign_pointer() - +--------+ + +--------+ +---------------------->| reader |---------+ | +--------+ | | | | @@ -318,12 +318,12 @@ reader, updater, and reclaimer. | | | rcu_read_lock() | | | rcu_read_unlock() | rcu_dereference() | | - +---------+ | | - | updater |<---------------------+ | - +---------+ V + +---------+ | | + | updater |<----------------+ | + +---------+ V | +-----------+ +----------------------------------->| reclaimer | - +-----------+ + +-----------+ Defer: synchronize_rcu() & call_rcu() diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt index b8ca28b60215..7e71c9c1d8e9 100644 --- a/Documentation/accounting/psi.txt +++ b/Documentation/accounting/psi.txt @@ -56,12 +56,12 @@ situation from a state where some tasks are stalled but the CPU is still doing productive work. As such, time spent in this subset of the stall state is tracked separately and exported in the "full" averages. -The ratios are tracked as recent trends over ten, sixty, and three -hundred second windows, which gives insight into short term events as -well as medium and long term trends. The total absolute stall time is -tracked and exported as well, to allow detection of latency spikes -which wouldn't necessarily make a dent in the time averages, or to -average trends over custom time frames. +The ratios (in %) are tracked as recent trends over ten, sixty, and +three hundred second windows, which gives insight into short term events +as well as medium and long term trends. The total absolute stall time +(in us) is tracked and exported as well, to allow detection of latency +spikes which wouldn't necessarily make a dent in the time averages, +or to average trends over custom time frames. Cgroup2 interface ================= diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2b8ee90bb644..3c0646e28488 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -704,8 +704,11 @@ upon panic. This parameter reserves the physical memory region [offset, offset + size] for that kernel image. If '@offset' is omitted, then a suitable offset - is selected automatically. Check - Documentation/kdump/kdump.txt for further details. + is selected automatically. + [KNL, x86_64] select a region under 4G first, and + fall back to reserve region above 4G when '@offset' + hasn't been specified. + See Documentation/kdump/kdump.txt for further details. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory @@ -2544,6 +2547,38 @@ in the "bleeding edge" mini2440 support kernel at http://repo.or.cz/w/linux-2.6/mini2440.git + mitigations= + [X86,PPC,S390] Control optional mitigations for CPU + vulnerabilities. This is a set of curated, + arch-independent options, each of which is an + aggregation of existing arch-specific options. + + off + Disable all optional CPU mitigations. This + improves system performance, but it may also + expose users to several CPU vulnerabilities. + Equivalent to: nopti [X86,PPC] + nospectre_v1 [PPC] + nobp=0 [S390] + nospectre_v2 [X86,PPC,S390] + spectre_v2_user=off [X86] + spec_store_bypass_disable=off [X86,PPC] + l1tf=off [X86] + + auto (default) + Mitigate all CPU vulnerabilities, but leave SMT + enabled, even if it's vulnerable. This is for + users who don't want to be surprised by SMT + getting disabled across kernel upgrades, or who + have other ways of avoiding SMT-based attacks. + Equivalent to: (default behavior) + + auto,nosmt + Mitigate all CPU vulnerabilities, disabling SMT + if needed. This is for users who always want to + be fully mitigated, even if it means losing SMT. + Equivalent to: l1tf=flush,nosmt [X86] + mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this parameter allows control of the logging verbosity for @@ -3394,6 +3429,8 @@ bridges without forcing it upstream. Note: this removes isolation between devices and may put more devices in an IOMMU group. + force_floating [S390] Force usage of floating interrupts. + nomio [S390] Do not use MIO instructions. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. @@ -3623,7 +3660,9 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above. + The argument is a cpu list, as described above, + except that the string "all" can be used to + specify every CPU on the system. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. @@ -4703,6 +4742,10 @@ [x86] unstable: mark the TSC clocksource as unstable, this marks the TSC unconditionally unstable at bootup and avoids any further wobbles once the TSC watchdog notices. + [x86] nowatchdog: disable clocksource watchdog. Used + in situations with strict latency requirements (where + interruptions from clocksource watchdog are not + acceptable). turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt index 913396ac5824..dca3fb0554db 100644 --- a/Documentation/atomic_t.txt +++ b/Documentation/atomic_t.txt @@ -56,6 +56,23 @@ Barriers: smp_mb__{before,after}_atomic() +TYPES (signed vs unsigned) +----- + +While atomic_t, atomic_long_t and atomic64_t use int, long and s64 +respectively (for hysterical raisins), the kernel uses -fno-strict-overflow +(which implies -fwrapv) and defines signed overflow to behave like +2s-complement. + +Therefore, an explicitly unsigned variant of the atomic ops is strictly +unnecessary and we can simply cast, there is no UB. + +There was a bug in UBSAN prior to GCC-8 that would generate UB warnings for +signed types. + +With this we also conform to the C/C++ _Atomic behaviour and things like +P1236R1. + SEMANTICS --------- diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index 9a60a5d60e38..7313d354f20e 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -148,16 +148,16 @@ The ``btf_type.size * 8`` must be equal to or greater than ``BTF_INT_BITS()`` for the type. The maximum value of ``BTF_INT_BITS()`` is 128. The ``BTF_INT_OFFSET()`` specifies the starting bit offset to calculate values -for this int. For example, a bitfield struct member has: * btf member bit -offset 100 from the start of the structure, * btf member pointing to an int -type, * the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4`` +for this int. For example, a bitfield struct member has: + * btf member bit offset 100 from the start of the structure, + * btf member pointing to an int type, + * the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4`` Then in the struct memory layout, this member will occupy ``4`` bits starting from bits ``100 + 2 = 102``. Alternatively, the bitfield struct member can be the following to access the same bits as the above: - * btf member bit offset 102, * btf member pointing to an int type, * the int type has ``BTF_INT_OFFSET() = 0`` and ``BTF_INT_BITS() = 4`` diff --git a/Documentation/core-api/cachetlb.rst b/Documentation/core-api/cachetlb.rst index 6eb9d3f090cd..93cb65d52720 100644 --- a/Documentation/core-api/cachetlb.rst +++ b/Documentation/core-api/cachetlb.rst @@ -101,16 +101,6 @@ changes occur: translations for software managed TLB configurations. The sparc64 port currently does this. -6) ``void tlb_migrate_finish(struct mm_struct *mm)`` - - This interface is called at the end of an explicit - process migration. This interface provides a hook - to allow a platform to update TLB or context-specific - information for the address space. - - The ia64 sn2 platform is one example of a platform - that uses this interface. - Next, we have the cache flushing interfaces. In general, when Linux is changing an existing virtual-->physical mapping to a new value, the sequence will be in one of the following forms:: diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt index c6e7e9196a8b..cb61277e2308 100644 --- a/Documentation/cputopology.txt +++ b/Documentation/cputopology.txt @@ -3,79 +3,79 @@ How CPU topology info is exported via sysfs =========================================== Export CPU topology info via sysfs. Items (attributes) are similar -to /proc/cpuinfo output of some architectures: +to /proc/cpuinfo output of some architectures. They reside in +/sys/devices/system/cpu/cpuX/topology/: -1) /sys/devices/system/cpu/cpuX/topology/physical_package_id: +physical_package_id: physical package id of cpuX. Typically corresponds to a physical socket number, but the actual value is architecture and platform dependent. -2) /sys/devices/system/cpu/cpuX/topology/core_id: +core_id: the CPU core ID of cpuX. Typically it is the hardware platform's identifier (rather than the kernel's). The actual value is architecture and platform dependent. -3) /sys/devices/system/cpu/cpuX/topology/book_id: +book_id: the book ID of cpuX. Typically it is the hardware platform's identifier (rather than the kernel's). The actual value is architecture and platform dependent. -4) /sys/devices/system/cpu/cpuX/topology/drawer_id: +drawer_id: the drawer ID of cpuX. Typically it is the hardware platform's identifier (rather than the kernel's). The actual value is architecture and platform dependent. -5) /sys/devices/system/cpu/cpuX/topology/thread_siblings: +thread_siblings: internal kernel map of cpuX's hardware threads within the same core as cpuX. -6) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list: +thread_siblings_list: human-readable list of cpuX's hardware threads within the same core as cpuX. -7) /sys/devices/system/cpu/cpuX/topology/core_siblings: +core_siblings: internal kernel map of cpuX's hardware threads within the same physical_package_id. -8) /sys/devices/system/cpu/cpuX/topology/core_siblings_list: +core_siblings_list: human-readable list of cpuX's hardware threads within the same physical_package_id. -9) /sys/devices/system/cpu/cpuX/topology/book_siblings: +book_siblings: internal kernel map of cpuX's hardware threads within the same book_id. -10) /sys/devices/system/cpu/cpuX/topology/book_siblings_list: +book_siblings_list: human-readable list of cpuX's hardware threads within the same book_id. -11) /sys/devices/system/cpu/cpuX/topology/drawer_siblings: +drawer_siblings: internal kernel map of cpuX's hardware threads within the same drawer_id. -12) /sys/devices/system/cpu/cpuX/topology/drawer_siblings_list: +drawer_siblings_list: human-readable list of cpuX's hardware threads within the same drawer_id. -To implement it in an architecture-neutral way, a new source file, -drivers/base/topology.c, is to export the 6 to 12 attributes. The book -and drawer related sysfs files will only be created if CONFIG_SCHED_BOOK -and CONFIG_SCHED_DRAWER are selected. +Architecture-neutral, drivers/base/topology.c, exports these attributes. +However, the book and drawer related sysfs files will only be created if +CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are selected, respectively. -CONFIG_SCHED_BOOK and CONFIG_DRAWER are currently only used on s390, where -they reflect the cpu and cache hierarchy. +CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are currently only used on s390, +where they reflect the cpu and cache hierarchy. For an architecture to support this feature, it must define some of these macros in include/asm-XXX/topology.h:: @@ -98,10 +98,10 @@ To be consistent on all architectures, include/linux/topology.h provides default definitions for any of the above macros that are not defined by include/asm-XXX/topology.h: -1) physical_package_id: -1 -2) core_id: 0 -3) sibling_cpumask: just the given CPU -4) core_cpumask: just the given CPU +1) topology_physical_package_id: -1 +2) topology_core_id: 0 +3) topology_sibling_cpumask: just the given CPU +4) topology_core_cpumask: just the given CPU For architectures that don't support books (CONFIG_SCHED_BOOK) there are no default definitions for topology_book_id() and topology_book_cpumask(). diff --git a/Documentation/devicetree/bindings/arm/cpus.yaml b/Documentation/devicetree/bindings/arm/cpus.yaml index 365dcf384d73..82dd7582e945 100644 --- a/Documentation/devicetree/bindings/arm/cpus.yaml +++ b/Documentation/devicetree/bindings/arm/cpus.yaml @@ -228,7 +228,7 @@ patternProperties: - renesas,r9a06g032-smp - rockchip,rk3036-smp - rockchip,rk3066-smp - - socionext,milbeaut-m10v-smp + - socionext,milbeaut-m10v-smp - ste,dbx500-smp cpu-release-addr: diff --git a/Documentation/devicetree/bindings/hwmon/adc128d818.txt b/Documentation/devicetree/bindings/hwmon/adc128d818.txt index 08bab0e94d25..d0ae46d7bac3 100644 --- a/Documentation/devicetree/bindings/hwmon/adc128d818.txt +++ b/Documentation/devicetree/bindings/hwmon/adc128d818.txt @@ -26,7 +26,7 @@ Required node properties: Optional node properties: - - ti,mode: Operation mode (see above). + - ti,mode: Operation mode (u8) (see above). Example (operation mode 2): @@ -34,5 +34,5 @@ Example (operation mode 2): adc128d818@1d { compatible = "ti,adc128d818"; reg = <0x1d>; - ti,mode = <2>; + ti,mode = /bits/ 8 <2>; }; diff --git a/Documentation/devicetree/bindings/net/davinci_emac.txt b/Documentation/devicetree/bindings/net/davinci_emac.txt index 24c5cdaba8d2..ca83dcc84fb8 100644 --- a/Documentation/devicetree/bindings/net/davinci_emac.txt +++ b/Documentation/devicetree/bindings/net/davinci_emac.txt @@ -20,6 +20,8 @@ Required properties: Optional properties: - phy-handle: See ethernet.txt file in the same directory. If absent, davinci_emac driver defaults to 100/FULL. +- nvmem-cells: phandle, reference to an nvmem node for the MAC address +- nvmem-cell-names: string, should be "mac-address" if nvmem is to be used - ti,davinci-rmii-en: 1 byte, 1 means use RMII - ti,davinci-no-bd-ram: boolean, does EMAC have BD RAM? diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt index cfc376bc977a..a68621580584 100644 --- a/Documentation/devicetree/bindings/net/ethernet.txt +++ b/Documentation/devicetree/bindings/net/ethernet.txt @@ -10,15 +10,14 @@ Documentation/devicetree/bindings/phy/phy-bindings.txt. the boot program; should be used in cases where the MAC address assigned to the device by the boot program is different from the "local-mac-address" property; -- nvmem-cells: phandle, reference to an nvmem node for the MAC address; -- nvmem-cell-names: string, should be "mac-address" if nvmem is to be used; - max-speed: number, specifies maximum speed in Mbit/s supported by the device; - max-frame-size: number, maximum transfer unit (IEEE defined MTU), rather than the maximum frame size (there's contradiction in the Devicetree Specification). - phy-mode: string, operation mode of the PHY interface. This is now a de-facto standard property; supported values are: - * "internal" + * "internal" (Internal means there is not a standard bus between the MAC and + the PHY, something proprietary is being used to embed the PHY in the MAC.) * "mii" * "gmii" * "sgmii" diff --git a/Documentation/devicetree/bindings/net/macb.txt b/Documentation/devicetree/bindings/net/macb.txt index 174f292d8a3e..8b80515729d7 100644 --- a/Documentation/devicetree/bindings/net/macb.txt +++ b/Documentation/devicetree/bindings/net/macb.txt @@ -26,6 +26,10 @@ Required properties: Optional elements: 'tsu_clk' - clocks: Phandles to input clocks. +Optional properties: +- nvmem-cells: phandle, reference to an nvmem node for the MAC address +- nvmem-cell-names: string, should be "mac-address" if nvmem is to be used + Optional properties for PHY child node: - reset-gpios : Should specify the gpio for phy reset - magic-packet : If present, indicates that the hardware supports waking diff --git a/Documentation/driver-api/usb/power-management.rst b/Documentation/driver-api/usb/power-management.rst index 79beb807996b..4a74cf6f2797 100644 --- a/Documentation/driver-api/usb/power-management.rst +++ b/Documentation/driver-api/usb/power-management.rst @@ -370,11 +370,15 @@ autosuspend the interface's device. When the usage counter is = 0 then the interface is considered to be idle, and the kernel may autosuspend the device. -Drivers need not be concerned about balancing changes to the usage -counter; the USB core will undo any remaining "get"s when a driver -is unbound from its interface. As a corollary, drivers must not call -any of the ``usb_autopm_*`` functions after their ``disconnect`` -routine has returned. +Drivers must be careful to balance their overall changes to the usage +counter. Unbalanced "get"s will remain in effect when a driver is +unbound from its interface, preventing the device from going into +runtime suspend should the interface be bound to a driver again. On +the other hand, drivers are allowed to achieve this balance by calling +the ``usb_autopm_*`` functions even after their ``disconnect`` routine +has returned -- say from within a work-queue routine -- provided they +retain an active reference to the interface (via ``usb_get_intf`` and +``usb_put_intf``). Drivers using the async routines are responsible for their own synchronization and mutual exclusion. diff --git a/Documentation/features/time/modern-timekeeping/arch-support.txt b/Documentation/features/time/modern-timekeeping/arch-support.txt index 2855dfe2464d..1d46da165b75 100644 --- a/Documentation/features/time/modern-timekeeping/arch-support.txt +++ b/Documentation/features/time/modern-timekeeping/arch-support.txt @@ -15,7 +15,7 @@ | h8300: | ok | | hexagon: | ok | | ia64: | ok | - | m68k: | TODO | + | m68k: | ok | | microblaze: | ok | | mips: | ok | | nds32: | ok | diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 10f4499e677c..ee60e519438a 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -243,10 +243,10 @@ Optimization ^^^^^^^^^^^^ The Kprobe-optimizer doesn't insert the jump instruction immediately; -rather, it calls synchronize_sched() for safety first, because it's +rather, it calls synchronize_rcu() for safety first, because it's possible for a CPU to be interrupted in the middle of executing the -optimized region [3]_. As you know, synchronize_sched() can ensure -that all interruptions that were active when synchronize_sched() +optimized region [3]_. As you know, synchronize_rcu() can ensure +that all interruptions that were active when synchronize_rcu() was called are done, but only if CONFIG_PREEMPT=n. So, this version of kprobe optimization supports only kernels with CONFIG_PREEMPT=n [4]_. diff --git a/Documentation/lzo.txt b/Documentation/lzo.txt index f79934225d8d..ca983328976b 100644 --- a/Documentation/lzo.txt +++ b/Documentation/lzo.txt @@ -102,9 +102,11 @@ Byte sequences dictionary which is empty, and that it will always be invalid at this place. - 17 : bitstream version. If the first byte is 17, the next byte - gives the bitstream version (version 1 only). If the first byte - is not 17, the bitstream version is 0. + 17 : bitstream version. If the first byte is 17, and compressed + stream length is at least 5 bytes (length of shortest possible + versioned bitstream), the next byte gives the bitstream version + (version 1 only). + Otherwise, the bitstream version is 0. 18..21 : copy 0..3 literals state = (byte - 17) = 0..3 [ copy <state> literals ] diff --git a/Documentation/media/uapi/rc/rc-tables.rst b/Documentation/media/uapi/rc/rc-tables.rst index f460031d8531..177ac44fa0fa 100644 --- a/Documentation/media/uapi/rc/rc-tables.rst +++ b/Documentation/media/uapi/rc/rc-tables.rst @@ -623,7 +623,7 @@ the remote via /dev/input/event devices. - .. row 78 - - ``KEY_SCREEN`` + - ``KEY_ASPECT_RATIO`` - Select screen aspect ratio @@ -631,7 +631,7 @@ the remote via /dev/input/event devices. - .. row 79 - - ``KEY_ZOOM`` + - ``KEY_FULL_SCREEN`` - Put device into zoom/full screen mode diff --git a/Documentation/networking/bpf_flow_dissector.rst b/Documentation/networking/bpf_flow_dissector.rst new file mode 100644 index 000000000000..b375ae2ec2c4 --- /dev/null +++ b/Documentation/networking/bpf_flow_dissector.rst @@ -0,0 +1,126 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================== +BPF Flow Dissector +================== + +Overview +======== + +Flow dissector is a routine that parses metadata out of the packets. It's +used in the various places in the networking subsystem (RFS, flow hash, etc). + +BPF flow dissector is an attempt to reimplement C-based flow dissector logic +in BPF to gain all the benefits of BPF verifier (namely, limits on the +number of instructions and tail calls). + +API +=== + +BPF flow dissector programs operate on an ``__sk_buff``. However, only the +limited set of fields is allowed: ``data``, ``data_end`` and ``flow_keys``. +``flow_keys`` is ``struct bpf_flow_keys`` and contains flow dissector input +and output arguments. + +The inputs are: + * ``nhoff`` - initial offset of the networking header + * ``thoff`` - initial offset of the transport header, initialized to nhoff + * ``n_proto`` - L3 protocol type, parsed out of L2 header + +Flow dissector BPF program should fill out the rest of the ``struct +bpf_flow_keys`` fields. Input arguments ``nhoff/thoff/n_proto`` should be +also adjusted accordingly. + +The return code of the BPF program is either BPF_OK to indicate successful +dissection, or BPF_DROP to indicate parsing error. + +__sk_buff->data +=============== + +In the VLAN-less case, this is what the initial state of the BPF flow +dissector looks like:: + + +------+------+------------+-----------+ + | DMAC | SMAC | ETHER_TYPE | L3_HEADER | + +------+------+------------+-----------+ + ^ + | + +-- flow dissector starts here + + +.. code:: c + + skb->data + flow_keys->nhoff point to the first byte of L3_HEADER + flow_keys->thoff = nhoff + flow_keys->n_proto = ETHER_TYPE + +In case of VLAN, flow dissector can be called with the two different states. + +Pre-VLAN parsing:: + + +------+------+------+-----+-----------+-----------+ + | DMAC | SMAC | TPID | TCI |ETHER_TYPE | L3_HEADER | + +------+------+------+-----+-----------+-----------+ + ^ + | + +-- flow dissector starts here + +.. code:: c + + skb->data + flow_keys->nhoff point the to first byte of TCI + flow_keys->thoff = nhoff + flow_keys->n_proto = TPID + +Please note that TPID can be 802.1AD and, hence, BPF program would +have to parse VLAN information twice for double tagged packets. + + +Post-VLAN parsing:: + + +------+------+------+-----+-----------+-----------+ + | DMAC | SMAC | TPID | TCI |ETHER_TYPE | L3_HEADER | + +------+------+------+-----+-----------+-----------+ + ^ + | + +-- flow dissector starts here + +.. code:: c + + skb->data + flow_keys->nhoff point the to first byte of L3_HEADER + flow_keys->thoff = nhoff + flow_keys->n_proto = ETHER_TYPE + +In this case VLAN information has been processed before the flow dissector +and BPF flow dissector is not required to handle it. + + +The takeaway here is as follows: BPF flow dissector program can be called with +the optional VLAN header and should gracefully handle both cases: when single +or double VLAN is present and when it is not present. The same program +can be called for both cases and would have to be written carefully to +handle both cases. + + +Reference Implementation +======================== + +See ``tools/testing/selftests/bpf/progs/bpf_flow.c`` for the reference +implementation and ``tools/testing/selftests/bpf/flow_dissector_load.[hc]`` +for the loader. bpftool can be used to load BPF flow dissector program as well. + +The reference implementation is organized as follows: + * ``jmp_table`` map that contains sub-programs for each supported L3 protocol + * ``_dissect`` routine - entry point; it does input ``n_proto`` parsing and + does ``bpf_tail_call`` to the appropriate L3 handler + +Since BPF at this point doesn't support looping (or any jumping back), +jmp_table is used instead to handle multiple levels of encapsulation (and +IPv6 options). + + +Current Limitations +=================== +BPF flow dissector doesn't support exporting all the metadata that in-kernel +C-based implementation can export. Notable example is single VLAN (802.1Q) +and double VLAN (802.1AD) tags. Please refer to the ``struct bpf_flow_keys`` +for a set of information that's currently can be exported from the BPF context. diff --git a/Documentation/networking/decnet.txt b/Documentation/networking/decnet.txt index e12a4900cf72..d192f8b9948b 100644 --- a/Documentation/networking/decnet.txt +++ b/Documentation/networking/decnet.txt @@ -22,8 +22,6 @@ you'll need the following options as well... CONFIG_DECNET_ROUTER (to be able to add/delete routes) CONFIG_NETFILTER (will be required for the DECnet routing daemon) - CONFIG_DECNET_ROUTE_FWMARK is optional - Don't turn on SIOCGIFCONF support for DECnet unless you are really sure that you need it, in general you won't and it can cause ifconfig to malfunction. diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index 5449149be496..984e68f9e026 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -9,6 +9,7 @@ Contents: netdev-FAQ af_xdp batman-adv + bpf_flow_dissector can can_ucan_protocol device_drivers/freescale/dpaa2/index diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index acdfb5d2bcaa..c4ac35234f05 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -422,6 +422,7 @@ tcp_min_rtt_wlen - INTEGER minimum RTT when it is moved to a longer path (e.g., due to traffic engineering). A longer window makes the filter more resistant to RTT inflations such as transient congestion. The unit is seconds. + Possible values: 0 - 86400 (1 day) Default: 300 tcp_moderate_rcvbuf - BOOLEAN @@ -1336,6 +1337,7 @@ tag - INTEGER Default value is 0. xfrm4_gc_thresh - INTEGER + (Obsolete since linux-4.14) The threshold at which we will start garbage collecting for IPv4 destination cache entries. At twice this value the system will refuse new allocations. @@ -1919,6 +1921,7 @@ echo_ignore_all - BOOLEAN Default: 0 xfrm6_gc_thresh - INTEGER + (Obsolete since linux-4.14) The threshold at which we will start garbage collecting for IPv6 destination cache entries. At twice this value the system will refuse new allocations. diff --git a/Documentation/networking/netdev-FAQ.rst b/Documentation/networking/netdev-FAQ.rst index 8c7a713cf657..642fa963be3c 100644 --- a/Documentation/networking/netdev-FAQ.rst +++ b/Documentation/networking/netdev-FAQ.rst @@ -132,7 +132,7 @@ version that should be applied. If there is any doubt, the maintainer will reply and ask what should be done. Q: I made changes to only a few patches in a patch series should I resend only those changed? --------------------------------------------------------------------------------------------- +--------------------------------------------------------------------------------------------- A: No, please resend the entire patch series and make sure you do number your patches such that it is clear this is the latest and greatest set of patches that can be applied. diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt index 2df5894353d6..cd7303d7fa25 100644 --- a/Documentation/networking/rxrpc.txt +++ b/Documentation/networking/rxrpc.txt @@ -1009,16 +1009,18 @@ The kernel interface functions are as follows: (*) Check call still alive. - u32 rxrpc_kernel_check_life(struct socket *sock, - struct rxrpc_call *call); + bool rxrpc_kernel_check_life(struct socket *sock, + struct rxrpc_call *call, + u32 *_life); void rxrpc_kernel_probe_life(struct socket *sock, struct rxrpc_call *call); - The first function returns a number that is updated when ACKs are received - from the peer (notably including PING RESPONSE ACKs which we can elicit by - sending PING ACKs to see if the call still exists on the server). The - caller should compare the numbers of two calls to see if the call is still - alive after waiting for a suitable interval. + The first function passes back in *_life a number that is updated when + ACKs are received from the peer (notably including PING RESPONSE ACKs + which we can elicit by sending PING ACKs to see if the call still exists + on the server). The caller should compare the numbers of two calls to see + if the call is still alive after waiting for a suitable interval. It also + returns true as long as the call hasn't yet reached the completed state. This allows the caller to work out if the server is still contactable and if the call is still alive on the server while waiting for the server to diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 6af24cdb25cc..3f13d8599337 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -866,14 +866,14 @@ The intent is that compaction has less work to do in the future and to increase the success rate of future high-order allocations such as SLUB allocations, THP and hugetlbfs pages. -To make it sensible with respect to the watermark_scale_factor parameter, -the unit is in fractions of 10,000. The default value of 15,000 means -that up to 150% of the high watermark will be reclaimed in the event of -a pageblock being mixed due to fragmentation. The level of reclaim is -determined by the number of fragmentation events that occurred in the -recent past. If this value is smaller than a pageblock then a pageblocks -worth of pages will be reclaimed (e.g. 2MB on 64-bit x86). A boost factor -of 0 will disable the feature. +To make it sensible with respect to the watermark_scale_factor +parameter, the unit is in fractions of 10,000. The default value of +15,000 on !DISCONTIGMEM configurations means that up to 150% of the high +watermark will be reclaimed in the event of a pageblock being mixed due +to fragmentation. The level of reclaim is determined by the number of +fragmentation events that occurred in the recent past. If this value is +smaller than a pageblock then a pageblocks worth of pages will be reclaimed +(e.g. 2MB on 64-bit x86). A boost factor of 0 will disable the feature. ============================================================= diff --git a/Documentation/translations/ko_KR/memory-barriers.txt b/Documentation/translations/ko_KR/memory-barriers.txt index 7f01fb1c1084..db0b9d8619f1 100644 --- a/Documentation/translations/ko_KR/memory-barriers.txt +++ b/Documentation/translations/ko_KR/memory-barriers.txt @@ -493,10 +493,8 @@ CPU 에게 기대할 수 있는 최소한의 보장사항 몇가지가 있습니 이 타입의 오퍼레이션은 단방향의 투과성 배리어처럼 동작합니다. ACQUIRE 오퍼레이션 뒤의 모든 메모리 오퍼레이션들이 ACQUIRE 오퍼레이션 후에 일어난 것으로 시스템의 나머지 컴포넌트들에 보이게 될 것이 보장됩니다. - LOCK 오퍼레이션과 smp_load_acquire(), smp_cond_acquire() 오퍼레이션도 - ACQUIRE 오퍼레이션에 포함됩니다. smp_cond_acquire() 오퍼레이션은 컨트롤 - 의존성과 smp_rmb() 를 사용해서 ACQUIRE 의 의미적 요구사항(semantic)을 - 충족시킵니다. + LOCK 오퍼레이션과 smp_load_acquire(), smp_cond_load_acquire() 오퍼레이션도 + ACQUIRE 오퍼레이션에 포함됩니다. ACQUIRE 오퍼레이션 앞의 메모리 오퍼레이션들은 ACQUIRE 오퍼레이션 완료 후에 수행된 것처럼 보일 수 있습니다. @@ -2146,33 +2144,40 @@ set_current_state() 는 다음의 것들로 감싸질 수도 있습니다: event_indicated = 1; wake_up_process(event_daemon); -wake_up() 류에 의해 쓰기 메모리 배리어가 내포됩니다. 만약 그것들이 뭔가를 -깨운다면요. 이 배리어는 태스크 상태가 지워지기 전에 수행되므로, 이벤트를 -알리기 위한 STORE 와 태스크 상태를 TASK_RUNNING 으로 설정하는 STORE 사이에 -위치하게 됩니다. +wake_up() 이 무언가를 깨우게 되면, 이 함수는 범용 메모리 배리어를 수행합니다. +이 함수가 아무것도 깨우지 않는다면 메모리 배리어는 수행될 수도, 수행되지 않을 +수도 있습니다; 이 경우에 메모리 배리어를 수행할 거라 오해해선 안됩니다. 이 +배리어는 태스크 상태가 접근되기 전에 수행되는데, 자세히 말하면 이 이벤트를 +알리기 위한 STORE 와 TASK_RUNNING 으로 상태를 쓰는 STORE 사이에 수행됩니다: - CPU 1 CPU 2 + CPU 1 (Sleeper) CPU 2 (Waker) =============================== =============================== set_current_state(); STORE event_indicated smp_store_mb(); wake_up(); - STORE current->state <쓰기 배리어> - <범용 배리어> STORE current->state - LOAD event_indicated + STORE current->state ... + <범용 배리어> <범용 배리어> + LOAD event_indicated if ((LOAD task->state) & TASK_NORMAL) + STORE task->state -한번더 말합니다만, 이 쓰기 메모리 배리어는 이 코드가 정말로 뭔가를 깨울 때에만 -실행됩니다. 이걸 설명하기 위해, X 와 Y 는 모두 0 으로 초기화 되어 있다는 가정 -하에 아래의 이벤트 시퀀스를 생각해 봅시다: +여기서 "task" 는 깨어나지는 쓰레드이고 CPU 1 의 "current" 와 같습니다. + +반복하지만, wake_up() 이 무언가를 정말 깨운다면 범용 메모리 배리어가 수행될 +것이 보장되지만, 그렇지 않다면 그런 보장이 없습니다. 이걸 이해하기 위해, X 와 +Y 는 모두 0 으로 초기화 되어 있다는 가정 하에 아래의 이벤트 시퀀스를 생각해 +봅시다: CPU 1 CPU 2 =============================== =============================== - X = 1; STORE event_indicated + X = 1; Y = 1; smp_mb(); wake_up(); - Y = 1; wait_event(wq, Y == 1); - wake_up(); load from Y sees 1, no memory barrier - load from X might see 0 + LOAD Y LOAD X + +정말로 깨우기가 행해졌다면, 두 로드 중 (최소한) 하나는 1 을 보게 됩니다. +반면에, 실제 깨우기가 행해지지 않았다면, 두 로드 모두 0을 볼 수도 있습니다. -위 예제에서의 경우와 달리 깨우기가 정말로 행해졌다면, CPU 2 의 X 로드는 1 을 -본다고 보장될 수 있을 겁니다. +wake_up_process() 는 항상 범용 메모리 배리어를 수행합니다. 이 배리어 역시 +태스크 상태가 접근되기 전에 수행됩니다. 특히, 앞의 예제 코드에서 wake_up() 이 +wake_up_process() 로 대체된다면 두 로드 중 하나는 1을 볼 것이 보장됩니다. 사용 가능한 깨우기류 함수들로 다음과 같은 것들이 있습니다: @@ -2192,6 +2197,8 @@ wake_up() 류에 의해 쓰기 메모리 배리어가 내포됩니다. 만약 wake_up_poll(); wake_up_process(); +메모리 순서규칙 관점에서, 이 함수들은 모두 wake_up() 과 같거나 보다 강한 순서 +보장을 제공합니다. [!] 잠재우는 코드와 깨우는 코드에 내포되는 메모리 배리어들은 깨우기 전에 이루어진 스토어를 잠재우는 코드가 set_current_state() 를 호출한 후에 행하는 diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 67068c47c591..64b38dfcc243 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -321,7 +321,7 @@ cpu's hardware control block. 4.8 KVM_GET_DIRTY_LOG (vm ioctl) Capability: basic -Architectures: x86 +Architectures: all Type: vm ioctl Parameters: struct kvm_dirty_log (in/out) Returns: 0 on success, -1 on error @@ -3810,7 +3810,7 @@ to I/O ports. 4.117 KVM_CLEAR_DIRTY_LOG (vm ioctl) Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT -Architectures: x86 +Architectures: x86, arm, arm64, mips Type: vm ioctl Parameters: struct kvm_dirty_log (in) Returns: 0 on success, -1 on error @@ -3830,8 +3830,9 @@ The ioctl clears the dirty status of pages in a memory slot, according to the bitmap that is passed in struct kvm_clear_dirty_log's dirty_bitmap field. Bit 0 of the bitmap corresponds to page "first_page" in the memory slot, and num_pages is the size in bits of the input bitmap. -Both first_page and num_pages must be a multiple of 64. For each bit -that is set in the input bitmap, the corresponding page is marked "clean" +first_page must be a multiple of 64; num_pages must also be a multiple of +64 unless first_page + num_pages is the size of the memory slot. For each +bit that is set in the input bitmap, the corresponding page is marked "clean" in KVM's dirty bitmap, and dirty tracking is re-enabled for that page (for example via write-protection, or by clearing the dirty bit in a page table entry). @@ -4799,7 +4800,7 @@ and injected exceptions. 7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT -Architectures: all +Architectures: x86, arm, arm64, mips Parameters: args[0] whether feature should be enabled or not With this capability enabled, KVM_GET_DIRTY_LOG will not automatically diff --git a/Documentation/x86/kernel-stacks b/Documentation/x86/kernel-stacks index 9a0aa4d3a866..d1bfb0b95ee0 100644 --- a/Documentation/x86/kernel-stacks +++ b/Documentation/x86/kernel-stacks @@ -59,7 +59,7 @@ If that assumption is ever broken then the stacks will become corrupt. The currently assigned IST stacks are :- -* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). +* ESTACK_DF. EXCEPTION_STKSZ (PAGE_SIZE). Used for interrupt 8 - Double Fault Exception (#DF). @@ -68,7 +68,7 @@ The currently assigned IST stacks are :- Using a separate stack allows the kernel to recover from it well enough in many cases to still output an oops. -* NMI_STACK. EXCEPTION_STKSZ (PAGE_SIZE). +* ESTACK_NMI. EXCEPTION_STKSZ (PAGE_SIZE). Used for non-maskable interrupts (NMI). @@ -76,7 +76,7 @@ The currently assigned IST stacks are :- middle of switching stacks. Using IST for NMI events avoids making assumptions about the previous state of the kernel stack. -* DEBUG_STACK. DEBUG_STKSZ +* ESTACK_DB. EXCEPTION_STKSZ (PAGE_SIZE). Used for hardware debug interrupts (interrupt 1) and for software debug interrupts (INT3). @@ -86,7 +86,12 @@ The currently assigned IST stacks are :- avoids making assumptions about the previous state of the kernel stack. -* MCE_STACK. EXCEPTION_STKSZ (PAGE_SIZE). + To handle nested #DB correctly there exist two instances of DB stacks. On + #DB entry the IST stackpointer for #DB is switched to the second instance + so a nested #DB starts from a clean stack. The nested #DB switches + the IST stackpointer to a guard hole to catch triple nesting. + +* ESTACK_MCE. EXCEPTION_STKSZ (PAGE_SIZE). Used for interrupt 18 - Machine Check Exception (#MC). diff --git a/Documentation/x86/topology.txt b/Documentation/x86/topology.txt index 2953e3ec9a02..06b3cdbc4048 100644 --- a/Documentation/x86/topology.txt +++ b/Documentation/x86/topology.txt @@ -51,7 +51,7 @@ The topology of a system is described in the units of: The physical ID of the package. This information is retrieved via CPUID and deduced from the APIC IDs of the cores in the package. - - cpuinfo_x86.logical_id: + - cpuinfo_x86.logical_proc_id: The logical ID of the package. As we do not trust BIOSes to enumerate the packages in a consistent way, we introduced the concept of logical package diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt index 804f9426ed17..6cbe652d7a49 100644 --- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -72,7 +72,7 @@ Complete virtual memory map with 5-level page tables Notes: - With 56-bit addresses, user-space memory gets expanded by a factor of 512x, - from 0.125 PB to 64 PB. All kernel mappings shift down to the -64 PT starting + from 0.125 PB to 64 PB. All kernel mappings shift down to the -64 PB starting offset and many of the regions expand to support the much larger physical memory supported. @@ -83,7 +83,7 @@ Notes: 0000000000000000 | 0 | 00ffffffffffffff | 64 PB | user-space virtual memory, different per mm __________________|____________|__________________|_________|___________________________________________________________ | | | | - 0000800000000000 | +64 PB | ffff7fffffffffff | ~16K PB | ... huge, still almost 64 bits wide hole of non-canonical + 0100000000000000 | +64 PB | feffffffffffffff | ~16K PB | ... huge, still almost 64 bits wide hole of non-canonical | | | | virtual memory addresses up to the -64 PB | | | | starting offset of kernel mappings. __________________|____________|__________________|_________|___________________________________________________________ @@ -99,7 +99,7 @@ ____________________________________________________________|___________________ ffd2000000000000 | -11.5 PB | ffd3ffffffffffff | 0.5 PB | ... unused hole ffd4000000000000 | -11 PB | ffd5ffffffffffff | 0.5 PB | virtual memory map (vmemmap_base) ffd6000000000000 | -10.5 PB | ffdeffffffffffff | 2.25 PB | ... unused hole - ffdf000000000000 | -8.25 PB | fffffdffffffffff | ~8 PB | KASAN shadow memory + ffdf000000000000 | -8.25 PB | fffffbffffffffff | ~8 PB | KASAN shadow memory __________________|____________|__________________|_________|____________________________________________________________ | | Identical layout to the 47-bit one from here on: |