{RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage.
[ 1986.897016] kswapd0/16 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 1986.897023]  (&REISERFS_SB(s)->lock){+.+.?.}, at: [<c01f8bd4>] reiserfs_write_lock+0x20/0x2a
[ 1986.897044] {RECLAIM_FS-ON-W} state was registered at:
[ 1986.897050]   [<c014a5b9>] mark_held_locks+0xae/0xd0
[ 1986.897060]   [<c014aab3>] lockdep_trace_alloc+0x7d/0x91
[ 1986.897068]   [<c0190ee0>] kmem_cache_alloc+0x1a/0x93
[ 1986.897078]   [<c01e7728>] reiserfs_alloc_inode+0x13/0x3d
[ 1986.897088]   [<c01a5b06>] alloc_inode+0x14/0x5f
[ 1986.897097]   [<c01a5cb9>] iget5_locked+0x62/0x13a
[ 1986.897106]   [<c01e99e0>] reiserfs_fill_super+0x410/0x8b9
[ 1986.897114]   [<c01953da>] mount_bdev+0x10b/0x159
[ 1986.897123]   [<c01e764d>] get_super_block+0x10/0x12
[ 1986.897131]   [<c0195b38>] mount_fs+0x59/0x12d
[ 1986.897138]   [<c01a80d1>] vfs_kern_mount+0x45/0x7a
[ 1986.897147]   [<c01a83e3>] do_kern_mount+0x2f/0xb0
[ 1986.897155]   [<c01a987a>] do_mount+0x5c2/0x612
[ 1986.897163]   [<c01a9a72>] sys_mount+0x61/0x8f
[ 1986.897170]   [<c044060c>] sysenter_do_call+0x12/0x32
[ 1986.897181] irq event stamp: 7509691
[ 1986.897186] hardirqs last  enabled at (7509691): [<c0190f34>] kmem_cache_alloc+0x6e/0x93
[ 1986.897197] hardirqs last disabled at (7509690): [<c0190eea>] kmem_cache_alloc+0x24/0x93
[ 1986.897209] softirqs last  enabled at (7508896): [<c01294bd>] __do_softirq+0xee/0xfd
[ 1986.897222] softirqs last disabled at (7508859): [<c01030ed>] do_softirq+0x50/0x9d
[ 1986.897234]
[ 1986.897235] other info that might help us debug this:
[ 1986.897242]  Possible unsafe locking scenario:
[ 1986.897244]
[ 1986.897250]        CPU0
[ 1986.897254]        ----
[ 1986.897257]   lock(&REISERFS_SB(s)->lock);
[ 1986.897265] <Interrupt>
[ 1986.897269]     lock(&REISERFS_SB(s)->lock);
[ 1986.897276]
[ 1986.897277]  *** DEADLOCK ***
[ 1986.897278]
[ 1986.897286] no locks held by kswapd0/16.
[ 1986.897291]
[ 1986.897292] stack backtrace:
[ 1986.897299] Pid: 16, comm: kswapd0 Not tainted 3.1.1-main #8
[ 1986.897306] Call Trace:
[ 1986.897314]  [<c0439e76>] ? printk+0xf/0x11
[ 1986.897324]  [<c01482d1>] print_usage_bug+0x20e/0x21a
[ 1986.897332]  [<c01479b8>] ? print_irq_inversion_bug+0x172/0x172
[ 1986.897341]  [<c014855c>] mark_lock+0x27f/0x483
[ 1986.897349]  [<c0148d88>] __lock_acquire+0x628/0x1472
[ 1986.897358]  [<c0149fae>] lock_acquire+0x47/0x5e
[ 1986.897366]  [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a
[ 1986.897384]  [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a
[ 1986.897397]  [<c043b5ef>] mutex_lock_nested+0x35/0x26f
[ 1986.897409]  [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a
[ 1986.897421]  [<c01f8bd4>] reiserfs_write_lock+0x20/0x2a
[ 1986.897433]  [<c01e2edd>] map_block_for_writepage+0xc9/0x590
[ 1986.897448]  [<c01b1706>] ? create_empty_buffers+0x33/0x8f
[ 1986.897461]  [<c0121124>] ? get_parent_ip+0xb/0x31
[ 1986.897472]  [<c043ef7f>] ? sub_preempt_count+0x81/0x8e
[ 1986.897485]  [<c043cae0>] ? _raw_spin_unlock+0x27/0x3d
[ 1986.897496]  [<c0121124>] ? get_parent_ip+0xb/0x31
[ 1986.897508]  [<c01e355d>] reiserfs_writepage+0x1b9/0x3e7
[ 1986.897521]  [<c0173b40>] ? clear_page_dirty_for_io+0xcb/0xde
[ 1986.897533]  [<c014a6e3>] ? trace_hardirqs_on_caller+0x108/0x138
[ 1986.897546]  [<c014a71e>] ? trace_hardirqs_on+0xb/0xd
[ 1986.897559]  [<c0177b38>] shrink_page_list+0x34f/0x5e2
[ 1986.897572]  [<c01780a7>] shrink_inactive_list+0x172/0x22c
[ 1986.897585]  [<c0178464>] shrink_zone+0x303/0x3b1
[ 1986.897597]  [<c043cae0>] ? _raw_spin_unlock+0x27/0x3d
[ 1986.897611]  [<c01788c9>] kswapd+0x3b7/0x5f2

The deadlock shouldn't happen since we are doing that allocation in the
mount path, the filesystem is not available for any reclaim.  Still the
warning is annoying.

To solve this, acquire the lock later only where we need it, right before
calling reiserfs_read_locked_inode() that wants to lock to walk the tree.

Reported-by: Knut Petersen <Knut_Petersen@t-online.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hSÏú—4x