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Count and display through /proc/fs/fscache/stats the number of initialised
operations.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Out of line fscache_operation_init() so that it can access internal FS-Cache
features, such as stats, in a later commit.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Currently, fscache_cancel_op() only cancels pending operations - attempts to
cancel in-progress operations are ignored. This leads to a problem in
fscache_wait_for_operation_activation() whereby the wait is terminated, but
the object has been killed.
The check at the end of the function now triggers because it's no longer
contingent on the cache having produced an I/O error since the commit that
fixed the logic error in fscache_object_is_dead().
The result of the check is that it tries to cancel the operation - but since
the object may not be pending by this point, the cancellation request may be
ignored - with the result that the the object is just put by the caller and
fscache_put_operation has an assertion failure because the operation isn't in
either the COMPLETE or the CANCELLED states.
To fix this, we permit in-progress ops to be cancelled under some
circumstances.
The bug results in an oops that looks something like this:
FS-Cache: fscache_wait_for_operation_activation() = -ENOBUFS [obj dead 3]
FS-Cache:
FS-Cache: Assertion failed
FS-Cache: 3 == 5 is false
------------[ cut here ]------------
kernel BUG at ../fs/fscache/operation.c:432!
...
RIP: 0010:[<ffffffffa0088574>] fscache_put_operation+0xf2/0x2cd
Call Trace:
[<ffffffffa008b92a>] __fscache_read_or_alloc_pages+0x2ec/0x3b3
[<ffffffffa00b761f>] __nfs_readpages_from_fscache+0x59/0xbf [nfs]
[<ffffffffa00b06c5>] nfs_readpages+0x10c/0x185 [nfs]
[<ffffffff81124925>] ? alloc_pages_current+0x119/0x13e
[<ffffffff810ee5fd>] ? __page_cache_alloc+0xfb/0x10a
[<ffffffff810f87f8>] __do_page_cache_readahead+0x188/0x22c
[<ffffffff810f8b3a>] ondemand_readahead+0x29e/0x2af
[<ffffffff810f8c92>] page_cache_sync_readahead+0x38/0x3a
[<ffffffff810ef337>] generic_file_read_iter+0x1a2/0x55a
[<ffffffffa00a9dff>] ? nfs_revalidate_mapping+0xd6/0x288 [nfs]
[<ffffffffa00a6a23>] nfs_file_read+0x49/0x70 [nfs]
[<ffffffff811363be>] new_sync_read+0x78/0x9c
[<ffffffff81137164>] __vfs_read+0x13/0x38
[<ffffffff8113721e>] vfs_read+0x95/0x121
[<ffffffff811372f6>] SyS_read+0x4c/0x8a
[<ffffffff81557a52>] system_call_fastpath+0x12/0x17
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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fscache_object_is_dead() returns true only if the object is marked dead and
the cache got an I/O error. This should be a logical OR instead. Since two
of the callers got split up into handling for separate subcases, expand the
other callers and kill the function. This is probably the right thing to do
anyway since one of the subcases isn't about the object at all, but rather
about the cache.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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When an object is being marked as no longer live, do this under the object
spinlock to prevent a race with operation submission targeted on that object.
The problem occurs due to the following pair of intertwined sequences when the
cache tries to create an object that would take it over the hard available
space limit:
NETFS INTERFACE
===============
(A) The netfs calls fscache_acquire_cookie(). object creation is deferred to
the object state machine and the netfs is allowed to continue.
OBJECT STATE MACHINE KTHREAD
============================
(1) The object is looked up on disk by fscache_look_up_object()
calling cachefiles_walk_to_object(). The latter finds that the
object is not yet represented on disk and calls
fscache_object_lookup_negative().
(2) fscache_object_lookup_negative() sets FSCACHE_COOKIE_NO_DATA_YET
and clears FSCACHE_COOKIE_LOOKING_UP, thus allowing the netfs to
start queuing read operations.
(B) The netfs calls fscache_read_or_alloc_pages(). This calls
fscache_wait_for_deferred_lookup() which sees FSCACHE_COOKIE_LOOKING_UP
become clear, allowing the read to begin.
(C) A read operation is set up and passed to fscache_submit_op() to deal
with.
(3) cachefiles_walk_to_object() calls cachefiles_has_space(), which
fails (or one of the file operations to create stuff fails).
cachefiles returns an error to fscache.
(4) fscache_look_up_object() transits to the LOOKUP_FAILURE state,
(5) fscache_lookup_failure() sets FSCACHE_OBJECT_LOOKED_UP and
FSCACHE_COOKIE_UNAVAILABLE and clears FSCACHE_COOKIE_LOOKING_UP
then transits to the KILL_OBJECT state.
(6) fscache_kill_object() clears FSCACHE_OBJECT_IS_LIVE in an attempt
to reject any further requests from the netfs.
(7) object->n_ops is examined and found to be 0.
fscache_kill_object() transits to the DROP_OBJECT state.
(D) fscache_submit_op() locks the object spinlock, sees if it can dispatch
the op immediately by calling fscache_object_is_active() - which fails
since FSCACHE_OBJECT_IS_AVAILABLE has not yet been set.
(E) fscache_submit_op() then tests FSCACHE_OBJECT_LOOKED_UP - which is set.
It then queues the object and increments object->n_ops.
(8) fscache_drop_object() releases the object and eventually
fscache_put_object() calls cachefiles_put_object() which suffers
an assertion failure here:
ASSERTCMP(object->fscache.n_ops, ==, 0);
Locking the object spinlock in step (6) around the clearance of
FSCACHE_OBJECT_IS_LIVE ensures that the the decision trees in
fscache_submit_op() and fscache_submit_exclusive_op() don't see the IS_LIVE
flag being cleared mid-decision: either the op is queued before step (7) - in
which case fscache_kill_object() will see n_ops>0 and will deal with the op -
or the op will be rejected.
This, combined with rejecting op submission if the target object is dying, fix
the problem.
The problem shows up as the following oops:
CacheFiles: Assertion failed
CacheFiles: 1 == 0 is false
------------[ cut here ]------------
kernel BUG at ../fs/cachefiles/interface.c:339!
...
RIP: 0010:[<ffffffffa014fd9c>] [<ffffffffa014fd9c>] cachefiles_put_object+0x2a4/0x301 [cachefiles]
...
Call Trace:
[<ffffffffa008674b>] fscache_put_object+0x18/0x21 [fscache]
[<ffffffffa00883e6>] fscache_object_work_func+0x3ba/0x3c9 [fscache]
[<ffffffff81054dad>] process_one_work+0x226/0x441
[<ffffffff81055d91>] worker_thread+0x273/0x36b
[<ffffffff81055b1e>] ? rescuer_thread+0x2e1/0x2e1
[<ffffffff81059b9d>] kthread+0x10e/0x116
[<ffffffff81059a8f>] ? kthread_create_on_node+0x1bb/0x1bb
[<ffffffff815579ac>] ret_from_fork+0x7c/0xb0
[<ffffffff81059a8f>] ? kthread_create_on_node+0x1bb/0x1bb
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Reject new operations that are being submitted against an object if that
object has failed its lookup or creation states or has been killed by the
cache backend for some other reason, such as having been culled.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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When submitting an operation, prefer to cancel the operation immediately
rather than queuing it for later processing if the object is marked as dying
(ie. the object state machine has reached the KILL_OBJECT state).
Whilst we're at it, change the series of related test_bit() calls into a
READ_ONCE() and bitwise-AND operators to reduce the number of load
instructions (test_bit() has a volatile address).
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Move fscache_report_unexpected_submission() up within operation.c so that it
can be called from fscache_submit_exclusive_op() too.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Count the number of objects that get culled by the cache backend and the
number of objects that the cache backend declines to instantiate due to lack
of space in the cache.
These numbers are made available through /proc/fs/fscache/stats
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
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Instead of using the literal value for the number of nanoseconds per
second, use the macro instead to increase readability.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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Commit a7854487cd7128a30a7f4f5259de9f67d5efb95f:
md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.
Causes an RCW cycle to be forced even when the array is degraded.
A degraded array cannot support RCW as that requires reading all data
blocks, and one may be missing.
Forcing an RCW when it is not possible causes a live-lock and the code
spins, repeatedly deciding to do something that cannot succeed.
So change the condition to only force RCW on non-degraded arrays.
Reported-by: Manibalan P <pmanibalan@amiindia.co.in>
Bisected-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Tested-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f
Cc: stable@vger.kernel.org (v3.7+)
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The value resulting from the SECCOMP_RET_DATA mask could exceed MAX_ERRNO
when setting errno during a SECCOMP_RET_ERRNO filter action. This makes
sure we have a reliable value being set, so that an invalid errno will not
be ignored by userspace.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Dmitry V. Levin <ldv@altlinux.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fixes a potential corruption with uninitialized stack memory in the
seccomp BPF sample program.
[akpm@linux-foundation.org: coding-style fixlet]
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Robert Swiecki <swiecki@google.com>
Tested-by: Robert Swiecki <swiecki@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Call __set_current_state() instead of assigning the new state directly.
These interfaces also aid CONFIG_DEBUG_ATOMIC_SLEEP environments, keeping
track of who changed the state.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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While reporting the (refreshed) list of modules on automatic updates we
may hit the page boundary of the output console and cause a stop if
pagination is enabled. However, gdb does not accept user input while
running over the breakpoint handler. So we get stuck, and the user is
forced to interrupt gdb.
Resolve this by disabling pagination during automatic symbol updates. We
restore the user's configuration once done.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I'm proposing myself for keeping an eye on these scripts and integrating
contributions.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Yet another code simplification.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Analogously to the task list, convert the module list to a generator
function. It noticeably simplifies the code.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The iterator does not return any task_struct from the thread_group list
because the first condition in the 'if not t or ...' will only be the
first time None.
Instead of keeping track of the state ourself in the next() function, we
fall back using Python's generator.
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Using the gdb scripts leaves byte-compiled python files in the scripts/
directory. These should be ignored by git.
[jan.kiszka@siemens.com: drop redundant mrproper rule as suggested by Michal]
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I tried to use these scripts in an ubuntu 14.04 host (gdb 7.7 compiled
against python 3.3) but there were several errors.
I believe this patch fixes these issues so that the commands now work (I
tested lx-symbols, lx-dmesg, lx-lsmod).
Main issues that needed to be resolved:
* In python 2 iterators have a "next()" method. In python 3 it is
__next__() instead (so let's just add both).
* In older python versions there was an implicit conversion
in object.__format__() (used when an object is in string.format())
where it was converting the object to str first and then
calling str's __format__(). This has now been removed so
we must explicitly convert to str the objects for which
we need to keep this behavior.
* In dmesg.py: in python 3 log_buf is now a "memoryview" object
which needs to be converted to a string in order to use string
methods like "splitlines()". Luckily memoryview exists in
python 2.7.6 as well, so we can convert log_buf to memoryview
and use the same code in both python 2 and python 3.
This version of the patch has now been tested with gdb 7.7 and both python
3.4 and python 2.7.6 (I think asking for at least python 2.7.6 is a
reasonable requirement instead of complicating the code with version
checks etc).
Signed-off-by: Pantelis Koukousoulas <pktoss@gmail.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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David Howells
Thierry Reding
NeilBrown
Kees Cook
Davidlohr Bueso
Jan Kiszka
Daniel Wagner
Daniel Thompson
Pantelis Koukousoulas