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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html