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2008-01-25softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasksIngo Molnar1-1/+11
this patch extends the soft-lockup detector to automatically detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are printed the following way: ------------------> INFO: task prctl:3042 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message prctl D fd5e3793 0 3042 2997 f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286 f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000 f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b Call Trace: [<c04883a5>] schedule_timeout+0x6d/0x8b [<c04883d8>] schedule_timeout_uninterruptible+0x15/0x17 [<c0133a76>] msleep+0x10/0x16 [<c0138974>] sys_prctl+0x30/0x1e2 [<c0104c52>] sysenter_past_esp+0x5f/0xa5 ======================= 2 locks held by prctl/3042: #0: (&sb->s_type->i_mutex_key#5){--..}, at: [<c0197d11>] do_fsync+0x38/0x7a #1: (jbd_handle){--..}, at: [<c01ca3d2>] journal_start+0xc7/0xe9 <------------------ the current default timeout is 120 seconds. Such messages are printed up to 10 times per bootup. If the system has crashed already then the messages are not printed. if lockdep is enabled then all held locks are printed as well. this feature is a natural extension to the softlockup-detector (kernel locked up without scheduling) and to the NMI watchdog (kernel locked up with IRQs disabled). [ Gautham R Shenoy <ego@in.ibm.com>: CPU hotplug fixes. ] [ Andrew Morton <akpm@linux-foundation.org>: build warning fix. ] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-01-24lockdep: fix kernel crash on module unloadArjan van de Ven1-2/+5
Michael Wu noticed in his lkml post at http://marc.info/?l=linux-kernel&m=119396182726091&w=2 that certain wireless drivers ended up having their name in module memory, which would then crash the kernel on module unload. The patch he proposed was a bit clumsy in that it increased the size of a lockdep entry significantly; the patch below tries another approach, it checks, on module teardown, if the name of a class is in module space and then zaps the class. This is very similar to what we already do with keys that are in module space. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-16lockdep: fix internal double unlock during self-testNick Piggin1-4/+8
Lockdep, during self-test (when it was simulating double unlocks) was sometimes unconditionally unlocking a spinlock when it had not been locked. This won't work for ticket locks. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-12-07lockdep: make cli/sti annotation warnings clearerIngo Molnar1-4/+9
make cli/sti annotation warnings easier to interpret. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-12-05lockdep: in_range() fixOleg Nesterov1-12/+10
Torsten Kaiser wrote: | static inline int in_range(const void *start, const void *addr, const void *end) | { | return addr >= start && addr <= end; | } | This will return true, if addr is in the range of start (including) | to end (including). | | But debug_check_no_locks_freed() seems does: | const void *mem_to = mem_from + mem_len | -> mem_to is the last byte of the freed range, that fits in_range | lock_from = (void *)hlock->instance; | -> first byte of the lock | lock_to = (void *)(hlock->instance + 1); | -> first byte of the next lock, not last byte of the lock that is being checked! | | The test is: | if (!in_range(mem_from, lock_from, mem_to) && | !in_range(mem_from, lock_to, mem_to)) | continue; | So it tests, if the first byte of the lock is in the range that is freed ->OK | And if the first byte of the *next* lock is in the range that is freed | -> Not OK. We can also simplify in_range checks, we need only 2 comparisons, not 4. If the lock is not in memory range, it should be either at the left of range or at the right. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-12-05lockdep: fix debug_show_all_locks()Ingo Molnar1-0/+7
fix the oops that can be seen in: http://bugzilla.kernel.org/attachment.cgi?id=13828&action=view it is not safe to print the locks of running tasks. (even with this fix we have a small race - but this is a debug function after all.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-28lockdep: fix a typo in the __lock_acquire commentGautham R Shenoy1-1/+1
Fix a typo in the __lock_acquire comment. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-19Use helpers to obtain task pid in printksPavel Emelyanov1-11/+11
The task_struct->pid member is going to be deprecated, so start using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in the kernel. The first thing to start with is the pid, printed to dmesg - in this case we may safely use task_pid_nr(). Besides, printks produce more (much more) than a half of all the explicit pid usage. [akpm@linux-foundation.org: git-drm went and changed lots of stuff] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Dave Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19workqueue: debug flushing deadlocks with lockdepJohannes Berg1-1/+1
In the following scenario: code path 1: my_function() -> lock(L1); ...; flush_workqueue(); ... code path 2: run_workqueue() -> my_work() -> ...; lock(L1); ... you can get a deadlock when my_work() is queued or running but my_function() has acquired L1 already. This patch adds a pseudo-lock to each workqueue to make lockdep warn about this scenario. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Acked-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-11lockdep: syscall exit checkPeter Zijlstra1-0/+16
Provide a check to validate that we do not hold any locks when switching back to user-space. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-11lockdep: fix mismatched lockdep_depth/curr_chain_hashGregory Haskins1-5/+5
It is possible for the current->curr_chain_key to become inconsistent with the current index if the chain fails to validate. The end result is that future lock_acquire() operations may inadvertently fail to find a hit in the cache resulting in a new node being added to the graph for every acquire. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-19lockdep debugging: give stacktrace for init_errorJohannes Berg1-2/+11
When I started adding support for lockdep to 64-bit powerpc, I got a lockdep_init_error and with this patch was able to pinpoint why and where to put lockdep_init(). Let's support this generally for others adding lockdep support to their architecture. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockstat: measure lock bouncingPeter Zijlstra1-12/+26
__acquire | lock _____ | \ | __contended | | | wait | _______/ |/ | __acquired | __release | unlock We measure acquisition and contention bouncing. This is done by recording a cpu stamp in each lock instance. Contention bouncing requires the cpu stamp to be set on acquisition. Hence we move __acquired into the generic path. __acquired is then used to measure acquisition bouncing by comparing the current cpu with the old stamp before replacing it. __contended is used to measure contention bouncing (only useful for preemptable locks) [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockdep: various fixesPeter Zijlstra1-9/+12
- update the copyright notices - use the default hash function - fix a thinko in a BUILD_BUG_ON - add a WARN_ON to spot inconsitent naming - fix a termination issue in /proc/lock_stat [akpm@linux-foundation.org: cleanups] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockstat: human readability tweaksPeter Zijlstra1-0/+44
Present all this fancy new lock statistics information: *warning, _wide_ output ahead* (output edited for purpose of brevity) # cat /proc/lock_stat lock_stat version 0.1 ----------------------------------------------------------------------------------------------------------------------------------------------------------------- class name contentions waittime-min waittime-max waittime-total acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------- &inode->i_mutex: 14458 6.57 398832.75 2469412.23 6768876 0.34 11398383.65 339410830.89 --------------- &inode->i_mutex 4486 [<ffffffff802a08f9>] pipe_wait+0x86/0x8d &inode->i_mutex 0 [<ffffffff802a01e8>] pipe_write_fasync+0x29/0x5d &inode->i_mutex 0 [<ffffffff802a0e18>] pipe_read+0x74/0x3a5 &inode->i_mutex 0 [<ffffffff802a1a6a>] do_lookup+0x81/0x1ae ................................................................................................................................................................. &inode->i_data.tree_lock-W: 491 0.27 62.47 493.89 2477833 0.39 468.89 1146584.25 &inode->i_data.tree_lock-R: 65 0.44 4.27 48.78 26288792 0.36 184.62 10197458.24 -------------------------- &inode->i_data.tree_lock 46 [<ffffffff80277095>] __do_page_cache_readahead+0x69/0x24f &inode->i_data.tree_lock 31 [<ffffffff8026f9fb>] add_to_page_cache+0x31/0xba &inode->i_data.tree_lock 0 [<ffffffff802770ee>] __do_page_cache_readahead+0xc2/0x24f &inode->i_data.tree_lock 0 [<ffffffff8026f6e4>] find_get_page+0x1a/0x58 ................................................................................................................................................................. proc_inum_idr.lock: 0 0.00 0.00 0.00 36 0.00 65.60 148.26 proc_subdir_lock: 0 0.00 0.00 0.00 3049859 0.00 106.81 1563212.42 shrinker_rwsem-W: 0 0.00 0.00 0.00 5 0.00 1.73 3.68 shrinker_rwsem-R: 0 0.00 0.00 0.00 633 2.57 246.57 10909.76 'contentions' and 'acquisitions' are the number of such events measured (since the last reset). The waittime- and holdtime- (min, max, total) numbers are presented in microseconds. If there are any contention points, the lock class is presented in the block format (as i_mutex and tree_lock above), otherwise a single line of output is presented. The output is sorted on absolute number of contentions (read + write), this should get the worst offenders presented first, so that: # grep : /proc/lock_stat | head will quickly show who's bad. The stats can be reset using: # echo 0 > /proc/lock_stat [bunk@stusta.de: make 2 functions static] [akpm@linux-foundation.org: fix printk warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockstat: core infrastructurePeter Zijlstra1-0/+247
Introduce the core lock statistics code. Lock statistics provides lock wait-time and hold-time (as well as the count of corresponding contention and acquisitions events). Also, the first few call-sites that encounter contention are tracked. Lock wait-time is the time spent waiting on the lock. This provides insight into the locking scheme, that is, a heavily contended lock is indicative of a too coarse locking scheme. Lock hold-time is the duration the lock was held, this provides a reference for the wait-time numbers, so they can be put into perspective. 1) lock 2) ... do stuff .. unlock 3) The time between 1 and 2 is the wait-time. The time between 2 and 3 is the hold-time. The lockdep held-lock tracking code is reused, because it already collects locks into meaningful groups (classes), and because it is an existing infrastructure for lock instrumentation. Currently lockdep tracks lock acquisition with two hooks: lock() lock_acquire() _lock() ... code protected by lock ... unlock() lock_release() _unlock() We need to extend this with two more hooks, in order to measure contention. lock_contended() - used to measure contention events lock_acquired() - completion of the contention These are then placed the following way: lock() lock_acquire() if (!_try_lock()) lock_contended() _lock() lock_acquired() ... do locked stuff ... unlock() lock_release() _unlock() (Note: the try_lock() 'trick' is used to avoid instrumenting all platform dependent lock primitive implementations.) It is also possible to toggle the two lockdep features at runtime using: /proc/sys/kernel/prove_locking /proc/sys/kernel/lock_stat (esp. turning off the O(n^2) prove_locking functionaliy can help) [akpm@linux-foundation.org: build fixes] [akpm@linux-foundation.org: nuke unneeded ifdefs] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockdep: reduce the ifdefferyPeter Zijlstra1-543/+628
Move code around to get fewer but larger #ifdef sections. Break some in-function #ifdefs out into their own functions. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19lockdep: sanitise CONFIG_PROVE_LOCKINGPeter Zijlstra1-1/+12
Ensure that all of the lock dependency tracking code is under CONFIG_PROVE_LOCKING. This allows us to use the held lock tracking code for other purposes. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17kallsyms: make KSYM_NAME_LEN include space for trailing '\0'Tejun Heo1-2/+2
KSYM_NAME_LEN is peculiar in that it does not include the space for the trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating buffer. This is nonsense and error-prone. Moreover, when the caller forgets that it's very likely to subtly bite back by corrupting the stack because the last position of the buffer is always cleared to zero. This patch increments KSYM_NAME_LEN by one and updates code accordingly. * off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro is fixed. * Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together, MODULE_NAME_LEN was treated as if it didn't include space for the trailing '\0'. Fix it. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Paulo Marques <pmarques@grupopie.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08lockdep: removed unused ip argument in mark_lock & mark_held_locksJarek Poplawski1-23/+15
It looks like a remainder from designing... Signed-off-by: Jarek Poplawski <jarkao@o2.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08lockdep: lookup_chain_cache comment errataJarek Poplawski1-2/+3
Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08Simplify kallsyms_lookup()Alexey Dobriyan1-4/+1
Several kallsyms_lookup() pass dummy arguments but only need, say, module's name. Make kallsyms_lookup() accept NULLs where possible. Also, makes picture clearer about what interfaces are needed for all symbol resolving business. Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08simplify the stacktrace codeChristoph Hellwig1-2/+1
Simplify the stacktrace code: - remove the unused task argument to save_stack_trace, it's always current - remove the all_contexts flag, it's alwasy 0 Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andi Kleen <ak@suse.de> Cc: Akinobu Mita <akinobu.mita@gmail.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-22[PATCH] lockdep: debug_show_all_locks & debug_show_held_locks vs. debug_locksJarek Poplawski1-0/+8
lockdep's data shouldn't be used when debug_locks == 0 because it's not updated after this, so it's more misleading than helpful. PS: probably lockdep's current-> fields should be reset after it turns debug_locks off: so, after printing a bug report, but before return from exported functions, but there are really a lot of these possibilities (e.g. after DEBUG_LOCKS_WARN_ON), so, something could be missed. (Of course direct use of this fields isn't recommended either.) Reported-by: Folkert van Heusden <folkert@vanheusden.com> Inspired-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-01[PATCH] fix section mismatch warning in lockdepSam Ravnborg1-1/+1
lockdep_init() is marked __init but used in several places outside __init code. This causes following warnings: $ scripts/mod/modpost kernel/lockdep.o WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_init_map after 'lockdep_init_map' (at offset 0x105) WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.lockdep_reset_lock after 'lockdep_reset_lock' (at offset 0x35) WARNING: kernel/built-in.o - Section mismatch: reference to .init.text:lockdep_init from .text.__lock_acquire after '__lock_acquire' (at offset 0xb2) The warnings are less obviously due to heavy inlining by gcc - this is not altered. Fix the section mismatch warnings by removing the __init marking, which seems obviously wrong. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-20[PATCH] lockdep: debug_locks check after check_chain_keyJarek Poplawski1-0/+4
In __lock_acquire check_chain_key can turn off debug_locks, so check is needed to assure proper return code. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] lockdep: add graph depth information to /proc/lockdepJason Baron1-7/+12
Generate locking graph information into /proc/lockdep, for lock hierarchy documentation and visualization purposes. sample output: c089fd5c OPS: 138 FD: 14 BD: 1 --..: &tty->termios_mutex -> [c07a3430] tty_ldisc_lock -> [c07a37f0] &port_lock_key -> [c07afdc0] &rq->rq_lock_key#2 The lock classes listed are all the first-hop lock dependencies that lockdep has seen so far. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11[PATCH] lockdep: more unlock-on-error fixesJarek Poplawski1-4/+19
- returns after DEBUG_LOCKS_WARN_ON added in 3 places - debug_locks checking after lookup_chain_cache() added in __lock_acquire() - locking for testing and changing global variable max_lockdep_depth added in __lock_acquire() From: Ingo Molnar <mingo@elte.hu> My __acquire_lock() cleanup introduced a locking bug: on SMP systems we'd release a non-owned graph lock. Fix this by moving the graph unlock back, and by leaving the max_lockdep_depth variable update possibly racy. (we dont care, it's just statistics) Also add some minimal debugging code to graph_unlock()/graph_lock(), which caught this locking bug. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-12-30[PATCH] lockdep: printk warning fixAndrew Morton1-2/+6
kernel/lockdep.c: In function `lookup_chain_cache': kernel/lockdep.c:1339: warning: long long unsigned int format, u64 arg (arg 2) kernel/lockdep.c:1344: warning: long long unsigned int format, u64 arg (arg 2) Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: fix possible races while disabling lock-debuggingIngo Molnar1-65/+105
Jarek Poplawski noticed that lockdep global state could be accessed in a racy way if one CPU did a lockdep assert (shutting lockdep down), while the other CPU would try to do something that changes its global state. This patch fixes those races and cleans up lockdep's internal locking by adding a graph_lock()/graph_unlock()/debug_locks_off_graph_unlock helpers. (Also note that as we all know the Linux kernel is, by definition, bug-free and perfect, so this code never triggers, so these fixes are highly theoretical. I wrote this patch for aesthetic reasons alone.) [akpm@osdl.org: build fix] [jarkao2@o2.pl: build fix's refix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: print irq-trace info on assertsIngo Molnar1-5/+1
When we print an assert due to scheduling-in-atomic bugs, and if lockdep is enabled, then the IRQ tracing information of lockdep can be printed to pinpoint the code location that disabled interrupts. This saved me quite a bit of debugging time in cases where the backtrace did not identify the irq-disabling site well enough. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: use chain hash on CONFIG_DEBUG_LOCKDEP tooIngo Molnar1-8/+0
CONFIG_DEBUG_LOCKDEP is unacceptably slow because it does not utilize the chain-hash. Turn the chain-hash back on in this case too. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: clean up VERY_VERBOSE defineIngo Molnar1-3/+1
Cleanup: the VERY_VERBOSE define was unnecessarily dependent on #ifdef VERBOSE - while the VERBOSE switch is 0 or 1 (always defined). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: improve lockdep_reset()Ingo Molnar1-0/+3
Clear all the chains during lockdep_reset(). This fixes some locking-selftest false positives i saw on -rt. (never saw those on mainline though, but it could happen.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: improve verbose messagesIngo Molnar1-2/+6
Make verbose lockdep messages (off by default) more informative by printing out the hash chain key. (this patch was what helped me catch the earlier lockdep hash-collision bug) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13[PATCH] lockdep: filter off by defaultIngo Molnar1-2/+2
Fix typo in the class_filter() function. (filtering is not used by default so this only affects lockdep-internal debugging cases) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6Linus Torvalds1-4/+0
* 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6: (156 commits) [PATCH] x86-64: Export smp_call_function_single [PATCH] i386: Clean up smp_tune_scheduling() [PATCH] unwinder: move .eh_frame to RODATA [PATCH] unwinder: fully support linker generated .eh_frame_hdr section [PATCH] x86-64: don't use set_irq_regs() [PATCH] x86-64: check vector in setup_ioapic_dest to verify if need setup_IO_APIC_irq [PATCH] x86-64: Make ix86 default to HIGHMEM4G instead of NOHIGHMEM [PATCH] i386: replace kmalloc+memset with kzalloc [PATCH] x86-64: remove remaining pc98 code [PATCH] x86-64: remove unused variable [PATCH] x86-64: Fix constraints in atomic_add_return() [PATCH] x86-64: fix asm constraints in i386 atomic_add_return [PATCH] x86-64: Correct documentation for bzImage protocol v2.05 [PATCH] x86-64: replace kmalloc+memset with kzalloc in MTRR code [PATCH] x86-64: Fix numaq build error [PATCH] x86-64: include/asm-x86_64/cpufeature.h isn't a userspace header [PATCH] unwinder: Add debugging output to the Dwarf2 unwinder [PATCH] x86-64: Clarify error message in GART code [PATCH] x86-64: Fix interrupt race in idle callback (3rd try) [PATCH] x86-64: Remove unwind stack pointer alignment forcing again ... Fixed conflict in include/linux/uaccess.h manually Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] lockdep: register_lock_class() fixIngo Molnar1-0/+6
The hash_lock must only ever be taken with irqs disabled. This happens in all the important places, except one codepath: register_lock_class(). The race should trigger rarely because register_lock_class() is quite rare and single-threaded (happens during init most of the time). The fix is to disable irqs. ( bug found live in -rt: there preemption is alot more agressive and preempting with the hash-lock held caused a lockup.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] remove kernel/lockdep.c:lockdep_internalAdrian Bunk1-7/+0
Remove the no longer used lockdep_internal(). Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] lockdep: misc fixes in lockdep.cJarek Poplawski1-3/+6
- numeric string size replaced with constant in print_lock_name and print_lockdep_cache, - return on null pointer in print_lock_dependencies, - one more lockdep return with 0 with unlocking fix in mark_lock. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] lockdep: internal locking fixesJarek Poplawski1-10/+15
Here are mainly some lockdep returns with 0 with unlocking fixes. Signed-off-by: Jarek Poplawski <jarkao2@o2.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] lockdep: annotate nfs/nfsd in-kernel socketsPeter Zijlstra1-0/+1
Stick NFS sockets in their own class to avoid some lockdep warnings. NFS sockets are never exposed to user-space, and will hence not trigger certain code paths that would otherwise pose deadlock scenarios. [akpm@osdl.org: cleanups] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Steven Dickson <SteveD@redhat.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Acked-by: Neil Brown <neilb@suse.de> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> [ Fixed patch corruption by quilt, pointed out by Peter Zijlstra ] Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] unwinder: Remove lockdep disabling of nested locks for unwinderAndi Kleen1-4/+0
Shouldn't be needed anymore since __kernel_text_address is used unconditionally on x86-64 Signed-off-by: Andi Kleen <ak@suse.de>
2006-11-17[PATCH] lockdep: fix static keys in module-allocated percpu areasIngo Molnar1-1/+2
lockdep got confused by certain locks in modules: INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. Call Trace: [<ffffffff8026f40d>] dump_trace+0xaa/0x3f2 [<ffffffff8026f78f>] show_trace+0x3a/0x60 [<ffffffff8026f9d1>] dump_stack+0x15/0x17 [<ffffffff802abfe8>] __lock_acquire+0x724/0x9bb [<ffffffff802ac52b>] lock_acquire+0x4d/0x67 [<ffffffff80267139>] rt_spin_lock+0x3d/0x41 [<ffffffff8839ed3f>] :ip_conntrack:__ip_ct_refresh_acct+0x131/0x174 [<ffffffff883a1334>] :ip_conntrack:udp_packet+0xbf/0xcf [<ffffffff8839f9af>] :ip_conntrack:ip_conntrack_in+0x394/0x4a7 [<ffffffff8023551f>] nf_iterate+0x41/0x7f [<ffffffff8025946a>] nf_hook_slow+0x64/0xd5 [<ffffffff802369a2>] ip_rcv+0x24e/0x506 [...] Steven Rostedt found the bug: static_obj() check did not take PERCPU_ENOUGH_ROOM into account, so in-module DEFINE_PER_CPU-area locks were triggering this message. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-17Merge git://git.kernel.org/pub/scm/linux/kernel/git/dtor/inputLinus Torvalds1-4/+6
* git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: Input: fm801-gp - handle errors from pci_enable_device() Input: gameport core - handle errors returned by device_bind_driver() Input: serio core - handle errors returned by device_bind_driver() Lockdep: fix compile error in drivers/input/serio/serio.c Input: serio - add lockdep annotations Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass() Input: atkbd - supress "too many keys" error message Input: i8042 - supress ACK/NAKs when blinking during panic Input: add missing exports to fix modular build
2006-10-17[PATCH] lockdep: increase max allowed recursion depthIngo Molnar1-3/+5
In general, lockdep warnings are intended to be non-fatal, so I have put in various practical limits on internal data structure failure modes. We haven't had a /single/ lockdep-internal crash ever since lockdep went upstream [the unwinder crashes are outside of lockdep], and that's largely due to the good internal checks it does. Recursion within the dependency graph is currently limited to 20, that's probably not enough on some many-CPU boxes - this patch doubles it to 40. I have written the lockdep functions to have as small stackframes as possible, so 40 should be OK too. (The practical recursion limit should be somewhere between 100 and 200 entries. If we hit that then I'll change the algorithm to be iteration-based. Graph walking logic is so easy to program via recursion, so i'd like to keep recursion as long as possible.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-11[PATCH] lockdep: use BUILD_BUG_ONAlexey Dobriyan1-4/+1
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-11Lockdep: add lockdep_set_class_and_subclass() and lockdep_set_subclass()Peter Zijlstra1-4/+6
This annotation makes it possible to assign a subclass on lock init. This annotation is meant to reduce the _nested() annotations by assigning a default subclass. One could do without this annotation and rely on lockdep_set_class() exclusively, but that would require a manual stack of struct lock_class_key objects. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2006-10-02[PATCH] namespaces: utsname: use init_utsname when appropriateSerge E. Hallyn1-3/+3
In some places, particularly drivers and __init code, the init utsns is the appropriate one to use. This patch replaces those with a the init_utsname helper. Changes: Removed several uses of init_utsname(). Hope I picked all the right ones in net/ipv4/ipconfig.c. These are now changed to utsname() (the per-process namespace utsname) in the previous patch (2/7) [akpm@osdl.org: CIFS fix] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Andrey Savochkin <saw@sw.ru> Cc: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29[PATCH] lockdep core: improve the lock-chain-hashIngo Molnar1-2/+2
With CONFIG_DEBUG_LOCK_ALLOC turned off i was getting sporadic failures in the locking self-test: ------------> | Locking API testsuite: ---------------------------------------------------------------------------- | spin |wlock |rlock |mutex | wsem | rsem | -------------------------------------------------------------------------- A-A deadlock: ok | ok | ok | ok | ok | ok | A-B-B-A deadlock: ok | ok | ok | ok | ok | ok | A-B-B-C-C-A deadlock: ok | ok | ok | ok | ok | ok | A-B-C-A-B-C deadlock: ok | ok | ok | ok | ok | ok | A-B-B-C-C-D-D-A deadlock: ok |FAILED| ok | ok | ok | ok | A-B-C-D-B-D-D-A deadlock: ok | ok | ok | ok | ok | ok | A-B-C-D-B-C-D-A deadlock: ok | ok | ok | ok | ok |FAILED| after much debugging it turned out to be caused by accidental chain-hash key collisions. The current hash is: #define iterate_chain_key(key1, key2) \ (((key1) << MAX_LOCKDEP_KEYS_BITS/2) ^ \ ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \ (key2)) where MAX_LOCKDEP_KEYS_BITS is 11. This hash is pretty good as it will shift by 5 bits in every iteration, where every new ID 'mixed' into the hash would have up to 11 bits. But because there was a 6 bits overlap between subsequent IDs and their high bits tended to be similar, there was a chance for accidental chain-hash collision for a low number of locks held. the solution is to shift by 11 bits: #define iterate_chain_key(key1, key2) \ (((key1) << MAX_LOCKDEP_KEYS_BITS) ^ \ ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS)) ^ \ (key2)) This keeps the hash perfect up to 5 locks held, but even above that the hash is still good because 11 bits is a relative prime to the total 64 bits, so a complete match will only occur after 64 held locks (which doesnt happen in Linux). Even after 5 locks held, entropy of the 5 IDs mixed into the hash is already good enough so that overlap doesnt generate a colliding hash ID. with this change the false positives went away. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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