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Date: Tue, 07 Jul 2009 20:51:54 -0700
From: Roland Dreier <rdreier@...co.com>
To: Miles Lane <miles.lane@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Alan Stern <stern@...land.harvard.edu>,
Greg KH <greg@...ah.com>,
Matthew Dharm <mdharm-usb@...-eyed-alien.net>,
David Brownell <dbrownell@...rs.sourceforge.net>,
Eric Paris <eparis@...hat.com>
Subject: Re: 2.6.31-rc2 -- INFO: inconsistent lock state -- inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
[ adding Eric Paris cc as this looks to be an inotify issue ]
> [ 6627.976224] =================================
> [ 6627.976237] [ INFO: inconsistent lock state ]
> [ 6627.976247] 2.6.31-rc2 #16
> [ 6627.976254] ---------------------------------
> [ 6627.976263] inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
> [ 6627.976276] khubd/217 [HC0[0]:SC0[0]:HE1:SE1] takes:
> [ 6627.976285] (iprune_mutex){+.+.?.}, at: [<c10ba899>]
> invalidate_inodes+0x20/0xe3
> [ 6627.976315] {IN-RECLAIM_FS-W} state was registered at:
> [ 6627.976324] [<c10536ab>] __lock_acquire+0x2c9/0xac4
> [ 6627.976343] [<c1053f45>] lock_acquire+0x9f/0xc2
> [ 6627.976358] [<c1308872>] __mutex_lock_common+0x2d/0x323
> [ 6627.976376] [<c1308c00>] mutex_lock_nested+0x2e/0x36
> [ 6627.976392] [<c10ba6ff>] shrink_icache_memory+0x38/0x1b2
> [ 6627.976407] [<c108bfb6>] shrink_slab+0xe2/0x13c
> [ 6627.976424] [<c108c3e1>] kswapd+0x3d1/0x55d
> [ 6627.976439] [<c10449b5>] kthread+0x66/0x6b
> [ 6627.976454] [<c1003fdf>] kernel_thread_helper+0x7/0x10
> [ 6627.976472] [<ffffffff>] 0xffffffff
> [ 6627.976494] irq event stamp: 41543
> [ 6627.976501] hardirqs last enabled at (41543): [<c13086f7>]
> __mutex_unlock_slowpath+0x10a/0x118
> [ 6627.976520] hardirqs last disabled at (41542): [<c1308645>]
> __mutex_unlock_slowpath+0x58/0x118
> [ 6627.976539] softirqs last enabled at (41158): [<c129d01f>]
> __rcu_read_unlock_bh+0x1c/0x1e
> [ 6627.976559] softirqs last disabled at (41156): [<c129cfcb>]
> __rcu_read_lock_bh+0x8/0x26
> [ 6627.976576]
> [ 6627.976579] other info that might help us debug this:
> [ 6627.976590] 2 locks held by khubd/217:
> [ 6627.976598] #0: (&type->s_umount_key#39){.+.+.+}, at:
> [<c10acd4b>] get_super+0x42/0x87
> [ 6627.976631] #1: (iprune_mutex){+.+.?.}, at: [<c10ba899>]
> invalidate_inodes+0x20/0xe3
> [ 6627.976657]
> [ 6627.976660] stack backtrace:
> [ 6627.976672] Pid: 217, comm: khubd Not tainted 2.6.31-rc2 #16
> [ 6627.976681] Call Trace:
> [ 6627.976696] [<c1307907>] ? printk+0xf/0x18
> [ 6627.976711] [<c10526d7>] valid_state+0x12a/0x13d
> [ 6627.976726] [<c10527ad>] mark_lock+0xc3/0x1b4
> [ 6627.976740] [<c1052eea>] ? check_usage_backwards+0x0/0x3f
> [ 6627.976755] [<c10528e1>] mark_held_locks+0x43/0x5b
> [ 6627.976772] [<c10cf46d>] ? inotify_ignored_and_remove_idr+0x19/0x74
> [ 6627.976787] [<c105299e>] lockdep_trace_alloc+0xa5/0xc1
> [ 6627.976802] [<c10a6685>] kmem_cache_alloc+0x21/0x13a
> [ 6627.976818] [<c10cf46d>] inotify_ignored_and_remove_idr+0x19/0x74
> [ 6627.976834] [<c10ceb77>] inotify_freeing_mark+0x8/0xa
> [ 6627.976849] [<c10cd989>] fsnotify_destroy_mark_by_entry+0xf1/0x115
> [ 6627.976858] [<c10cda32>] fsnotify_clear_marks_by_inode+0x85/0xa2
> [ 6627.976858] [<c10ccdbf>] __fsnotify_inode_delete+0x8/0xd
> [ 6627.976858] [<c10cd670>] fsnotify_unmount_inodes+0xb0/0xdf
> [ 6627.976858] [<c10ba8b9>] invalidate_inodes+0x40/0xe3
> [ 6627.976858] [<c10c977f>] __invalidate_device+0x21/0x38
> [ 6627.976858] [<c116c981>] invalidate_partition+0x1e/0x2d
> [ 6627.976858] [<c10e7710>] del_gendisk+0x2d/0xf0
> [ 6627.976858] [<c122e473>] sd_remove+0x35/0x67
> [ 6627.976858] [<c121b637>] __device_release_driver+0x47/0x7f
> [ 6627.976858] [<c121b70c>] device_release_driver+0x18/0x23
> [ 6627.976858] [<c121ad1b>] bus_remove_device+0x71/0x7e
> [ 6627.976858] [<c1219a0a>] device_del+0xf0/0x131
> [ 6627.976858] [<c122a4a6>] __scsi_remove_device+0x34/0x65
> [ 6627.976858] [<c12285a5>] scsi_forget_host+0x35/0x51
> [ 6627.976858] [<c1223615>] scsi_remove_host+0x69/0xd4
> [ 6627.976858] [<f805f67c>] quiesce_and_remove_host+0x4c/0x7e [usb_storage]
> [ 6627.976858] [<f805f760>] usb_stor_disconnect+0x11/0x1b [usb_storage]
> [ 6627.976858] [<c124adca>] usb_unbind_interface+0x4e/0xc4
> [ 6627.976858] [<c121b637>] __device_release_driver+0x47/0x7f
> [ 6627.976858] [<c121b70c>] device_release_driver+0x18/0x23
> [ 6627.976858] [<c121ad1b>] bus_remove_device+0x71/0x7e
> [ 6627.976858] [<c1219a0a>] device_del+0xf0/0x131
> [ 6627.976858] [<c1248795>] usb_disable_device+0xc1/0x125
> [ 6627.976858] [<c1243f37>] usb_disconnect+0xb2/0x117
> [ 6627.976858] [<c12450da>] hub_thread+0x533/0xe45
> [ 6627.976858] [<c13080fd>] ? schedule+0x70c/0x769
> [ 6627.976858] [<c1044bfc>] ? autoremove_wake_function+0x0/0x2f
> [ 6627.976858] [<c1244ba7>] ? hub_thread+0x0/0xe45
> [ 6627.976858] [<c10449b5>] kthread+0x66/0x6b
> [ 6627.976858] [<c104494f>] ? kthread+0x0/0x6b
> [ 6627.976858] [<c1003fdf>] kernel_thread_helper+0x7/0x10
> [ 6628.142547] usb 1-3:1.0: uevent
I don't believe that this is actually related to usb; it looks to be an
inotify issue (and I believe lockdep is warning about a real bug).
What lockdep is saying is that iprune_mutex is held during reclaim, when
it is taken in prune_icache(); however invalidate_inodes() also takes
iprune_mutex and then calls into fsnotify_unmount_inodes(), which ends
up in fsnotify_destroy_mark_by_entry(). And if inotify is in use, then
it calls into inotify_freeing_mark() via group->ops->freeing_mark, which
just does inotify_ignored_and_remove_idr().
And then if we look at this:
void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
struct fsnotify_group *group)
{
//..
event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
//...
fsnotify_add_notify_event(group, inotify_ignored_event, fsn_event_priv);
}
so it does a GFP_KERNEL allocation with iprune_mutex held; which could
deadlock if it triggers reclaim and ends up in prune_icache(). The
trivial fix for this immediate issue is:
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index ff27a29..b1727e8 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -379,7 +379,7 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
- event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
+ event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS);
if (unlikely(!event_priv))
goto skip_send_ignore;
but I don't think this fully fixes things -- notice that there is also
fsnotify_add_notify_event() there, which it seems might do
fsnotify_alloc_event_holder(), which is just
return kmem_cache_alloc(fsnotify_event_holder_cachep, GFP_KERNEL);
ie another GFP_KERNEL allocation that might happen with iprune_mutex
held. Again the simple fix is to change this to GFP_NOFS but I'm not
sure if it might not be better to pass a gfp mask in to know when we
might be in reclaim and when we might not be, to avoid failing
allocations and lost events.
Anyway, hope this helps...
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