The patch titled
inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive
has been added to the -mm tree. Its filename is
inotify-use-gfp_nofs-in-kernel_event-to-work-around-a-lockdep-false-positive.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive
From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
There is what we believe to be a false positive reported by lockdep.
inotify_inode_queue_event() => take inotify_mutex => kernel_event() =>
kmalloc() => SLOB => alloc_pages_node() => page reclaim => slab reclaim =>
dcache reclaim => inotify_inode_is_dead => take inotify_mutex => deadlock
The plan is to fix this via lockdep annotation, but that is proving to be
quite involved.
The patch flips the allocation over to GFP_NFS to shut the warning up, for
the 2.6.30 release.
Hopefully we will fix this for real in 2.6.31. I'll queue a patch in -mm
to switch it back to GFP_KERNEL so we don't forget.
[ 2668.325318]
[ 2668.325322] =================================
[ 2668.327448] [ INFO: inconsistent lock state ]
[ 2668.327448] 2.6.30-rc2-next-20090417 #203
[ 2668.327448] ---------------------------------
[ 2668.327448] inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage.
[ 2668.327448] kswapd0/380 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 2668.327448] (&inode->inotify_mutex){+.+.?.}, at: [<ffffffff8112f1b5>] inotify_inode_is_dead+0x35/0xb0
[ 2668.327448] {RECLAIM_FS-ON-W} state was registered at:
[ 2668.327448] [<ffffffff81079188>] mark_held_locks+0x68/0x90
[ 2668.327448] [<ffffffff810792a5>] lockdep_trace_alloc+0xf5/0x100
[ 2668.327448] [<ffffffff810f5261>] __kmalloc_node+0x31/0x1e0
[ 2668.327448] [<ffffffff81130652>] kernel_event+0xe2/0x190
[ 2668.327448] [<ffffffff81130826>] inotify_dev_queue_event+0x126/0x230
[ 2668.327448] [<ffffffff8112f096>] inotify_inode_queue_event+0xc6/0x110
[ 2668.327448] [<ffffffff8110444d>] vfs_create+0xcd/0x140
[ 2668.327448] [<ffffffff8110825d>] do_filp_open+0x88d/0xa20
[ 2668.327448] [<ffffffff810f6b68>] do_sys_open+0x98/0x140
[ 2668.327448] [<ffffffff810f6c50>] sys_open+0x20/0x30
[ 2668.327448] [<ffffffff8100c272>] system_call_fastpath+0x16/0x1b
[ 2668.327448] [<ffffffffffffffff>] 0xffffffffffffffff
[ 2668.327448] irq event stamp: 690455
[ 2668.327448] hardirqs last enabled at (690455): [<ffffffff81564fe4>] _spin_unlock_irqrestore+0x44/0x80
[ 2668.327448] hardirqs last disabled at (690454): [<ffffffff81565372>] _spin_lock_irqsave+0x32/0xa0
[ 2668.327448] softirqs last enabled at (690178): [<ffffffff81052282>] __do_softirq+0x202/0x220
[ 2668.327448] softirqs last disabled at (690157): [<ffffffff8100d50c>] call_softirq+0x1c/0x50
[ 2668.327448]
[ 2668.327448] other info that might help us debug this:
[ 2668.327448] 2 locks held by kswapd0/380:
[ 2668.327448] #0: (shrinker_rwsem){++++..}, at: [<ffffffff810d0bd7>] shrink_slab+0x37/0x180
[ 2668.327448] #1: (&type->s_umount_key#17){++++..}, at: [<ffffffff8110cfbf>] shrink_dcache_memory+0x11f/0x1e0
[ 2668.327448]
[ 2668.327448] stack backtrace:
[ 2668.327448] Pid: 380, comm: kswapd0 Not tainted 2.6.30-rc2-next-20090417 #203
[ 2668.327448] Call Trace:
[ 2668.327448] [<ffffffff810789ef>] print_usage_bug+0x19f/0x200
[ 2668.327448] [<ffffffff81018bff>] ? save_stack_trace+0x2f/0x50
[ 2668.327448] [<ffffffff81078f0b>] mark_lock+0x4bb/0x6d0
[ 2668.327448] [<ffffffff810799e0>] ? check_usage_forwards+0x0/0xc0
[ 2668.327448] [<ffffffff8107b142>] __lock_acquire+0xc62/0x1ae0
[ 2668.327448] [<ffffffff810f478c>] ? slob_free+0x10c/0x370
[ 2668.327448] [<ffffffff8107c0a1>] lock_acquire+0xe1/0x120
[ 2668.327448] [<ffffffff8112f1b5>] ? inotify_inode_is_dead+0x35/0xb0
[ 2668.327448] [<ffffffff81562d43>] mutex_lock_nested+0x63/0x420
[ 2668.327448] [<ffffffff8112f1b5>] ? inotify_inode_is_dead+0x35/0xb0
[ 2668.327448] [<ffffffff8112f1b5>] ? inotify_inode_is_dead+0x35/0xb0
[ 2668.327448] [<ffffffff81012fe9>] ? sched_clock+0x9/0x10
[ 2668.327448] [<ffffffff81077165>] ? lock_release_holdtime+0x35/0x1c0
[ 2668.327448] [<ffffffff8112f1b5>] inotify_inode_is_dead+0x35/0xb0
[ 2668.327448] [<ffffffff8110c9dc>] dentry_iput+0xbc/0xe0
[ 2668.327448] [<ffffffff8110cb23>] d_kill+0x33/0x60
[ 2668.327448] [<ffffffff8110ce23>] __shrink_dcache_sb+0x2d3/0x350
[ 2668.327448] [<ffffffff8110cffa>] shrink_dcache_memory+0x15a/0x1e0
[ 2668.327448] [<ffffffff810d0cc5>] shrink_slab+0x125/0x180
[ 2668.327448] [<ffffffff810d1540>] kswapd+0x560/0x7a0
[ 2668.327448] [<ffffffff810ce160>] ? isolate_pages_global+0x0/0x2c0
[ 2668.327448] [<ffffffff81065a30>] ? autoremove_wake_function+0x0/0x40
[ 2668.327448] [<ffffffff8107953d>] ? trace_hardirqs_on+0xd/0x10
[ 2668.327448] [<ffffffff810d0fe0>] ? kswapd+0x0/0x7a0
[ 2668.327448] [<ffffffff8106555b>] kthread+0x5b/0xa0
[ 2668.327448] [<ffffffff8100d40a>] child_rip+0xa/0x20
[ 2668.327448] [<ffffffff8100cdd0>] ? restore_args+0x0/0x30
[ 2668.327448] [<ffffffff81065500>] ? kthread+0x0/0xa0
[ 2668.327448] [<ffffffff8100d400>] ? child_rip+0x0/0x20
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Cc; Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/notify/inotify/inotify_user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/notify/inotify/inotify_user.c~inotify-use-gfp_nofs-in-kernel_event-to-work-around-a-lockdep-false-positive fs/notify/inotify/inotify_user.c
--- a/fs/notify/inotify/inotify_user.c~inotify-use-gfp_nofs-in-kernel_event-to-work-around-a-lockdep-false-positive
+++ a/fs/notify/inotify/inotify_user.c
@@ -220,7 +220,7 @@ static struct inotify_kernel_event * ker
rem = 0;
}
- kevent->name = kmalloc(len + rem, GFP_KERNEL);
+ kevent->name = kmalloc(len + rem, GFP_NOFS);
if (unlikely(!kevent->name)) {
kmem_cache_free(event_cachep, kevent);
return NULL;
_
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
vmscan-avoid-multiplication-overflow-in-shrink_zone.patch
linux-next.patch
inotify-use-gfp_nofs-in-kernel_event-to-work-around-a-lockdep-false-positive.patch
readahead-make-mmap_miss-an-unsigned-int.patch
readahead-move-max_sane_readahead-calls-into-force_page_cache_readahead.patch
readahead-apply-max_sane_readahead-limit-in-ondemand_readahead.patch
readahead-remove-one-unnecessary-radix-tree-lookup.patch
readahead-increase-interleaved-readahead-size.patch
readahead-remove-sync-async-readahead-call-dependency.patch
readahead-clean-up-and-simplify-the-code-for-filemap-page-fault-readahead.patch
readahead-sequential-mmap-readahead.patch
readahead-enforce-full-readahead-size-on-async-mmap-readahead.patch
readahead-record-mmap-read-around-states-in-file_ra_state.patch
radix-tree-add-radix_tree_prev_hole.patch
readahead-move-the-random-read-case-to-bottom.patch
readahead-introduce-context-readahead-algorithm.patch
readahead-introduce-context-readahead-algorithm-update.patch
readahead-remove-redundant-test-in-shrink_readahead_size_eio.patch
readahead-enforce-full-sync-mmap-readahead-size.patch
pagemap-document-clarifications.patch
pagemap-documentation-9-more-exported-page-flags.patch
mm-introduce-pagehuge-for-testing-huge-gigantic-pages.patch
proc-kpagecount-kpageflags-code-cleanup.patch
proc-export-more-page-flags-in-proc-kpageflags.patch
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