xfs mr_lock vs mmap_sem lock inversion?

From: Peter Zijlstra
Date: Tue Jul 14 2009 - 10:21:53 EST


Hi,

I seem to be getting lots (as in one every boot) of these:

[ 84.692079] =======================================================
[ 84.692082] [ INFO: possible circular locking dependency detected ]
[ 84.692084] 2.6.31-rc2-tip #179
[ 84.692086] -------------------------------------------------------
[ 84.692088] plasma/7446 is trying to acquire lock:
[ 84.692090] (&mm->mmap_sem){++++++}, at: [<ffffffff812d70d0>] do_page_fault+0x179/0x2a1
[ 84.692098]
[ 84.692098] but task is already holding lock:
[ 84.692100] (&(&ip->i_iolock)->mr_lock){++++++}, at: [<ffffffffa022ae30>] xfs_ilock+0x49/0x7e [xfs]
[ 84.692126]
[ 84.692127] which lock already depends on the new lock.
[ 84.692127]
[ 84.692129]
[ 84.692129] the existing dependency chain (in reverse order) is:
[ 84.692131]
[ 84.692131] -> #1 (&(&ip->i_iolock)->mr_lock){++++++}:
[ 84.692135] [<ffffffff8106bd61>] __lock_acquire+0xa62/0xbea
[ 84.692140] [<ffffffff8106bfe5>] lock_acquire+0xfc/0x128
[ 84.692143] [<ffffffff8105e3e7>] down_write_nested+0x2f/0x3b
[ 84.692147] [<ffffffffa022ae13>] xfs_ilock+0x2c/0x7e [xfs]
[ 84.692166] [<ffffffffa0243747>] xfs_free_eofblocks+0x11c/0x20a [xfs]
[ 84.692184] [<ffffffffa0244164>] xfs_release+0x138/0x145 [xfs]
[ 84.692203] [<ffffffffa024a00f>] xfs_file_release+0x15/0x19 [xfs]
[ 84.692221] [<ffffffff810e9e49>] __fput+0xfb/0x1a6
[ 84.692225] [<ffffffff810e9f11>] fput+0x1d/0x1f
[ 84.692228] [<ffffffff810cc45a>] remove_vma+0x3b/0x71
[ 84.692232] [<ffffffff810cd5a7>] do_munmap+0x309/0x32b
[ 84.692235] [<ffffffff810cd60e>] sys_munmap+0x45/0x5e
[ 84.692238] [<ffffffff8102cfcf>] sysenter_dispatch+0x7/0x33
[ 84.692242] [<ffffffffffffffff>] 0xffffffffffffffff
[ 84.692260]
[ 84.692260] -> #0 (&mm->mmap_sem){++++++}:
[ 84.692263] [<ffffffff8106bc55>] __lock_acquire+0x956/0xbea
[ 84.692267] [<ffffffff8106bfe5>] lock_acquire+0xfc/0x128
[ 84.692270] [<ffffffff812d3232>] down_read+0x34/0x40
[ 84.692273] [<ffffffff812d70d0>] do_page_fault+0x179/0x2a1
[ 84.692276] [<ffffffff812d4bf5>] page_fault+0x25/0x30
[ 84.692280] [<ffffffff810b2389>] generic_file_aio_read+0x364/0x5ba
[ 84.692284] [<ffffffffa024dfb3>] xfs_read+0x18d/0x1fa [xfs]
[ 84.692302] [<ffffffffa024a129>] xfs_file_aio_read+0x64/0x67 [xfs]
[ 84.692320] [<ffffffff810e8ac0>] do_sync_read+0xec/0x132
[ 84.692324] [<ffffffff810e95ba>] vfs_read+0xad/0x107
[ 84.692327] [<ffffffff810e96e2>] sys_read+0x4c/0x75
[ 84.692330] [<ffffffff8102cfcf>] sysenter_dispatch+0x7/0x33
[ 84.692333] [<ffffffffffffffff>] 0xffffffffffffffff
[ 84.692337]
[ 84.692338] other info that might help us debug this:
[ 84.692338]
[ 84.692340] 1 lock held by plasma/7446:
[ 84.692342] #0: (&(&ip->i_iolock)->mr_lock){++++++}, at: [<ffffffffa022ae30>] xfs_ilock+0x49/0x7e [xfs]
[ 84.692363]
[ 84.692364] stack backtrace:
[ 84.692366] Pid: 7446, comm: plasma Not tainted 2.6.31-rc2-tip #179
[ 84.692368] Call Trace:
[ 84.692372] [<ffffffff8106af89>] print_circular_bug_tail+0x71/0x7c
[ 84.692375] [<ffffffff8106bc55>] __lock_acquire+0x956/0xbea
[ 84.692379] [<ffffffff8106bfe5>] lock_acquire+0xfc/0x128
[ 84.692382] [<ffffffff812d70d0>] ? do_page_fault+0x179/0x2a1
[ 84.692385] [<ffffffff812d3232>] down_read+0x34/0x40
[ 84.692388] [<ffffffff812d70d0>] ? do_page_fault+0x179/0x2a1
[ 84.692391] [<ffffffff812d70d0>] do_page_fault+0x179/0x2a1
[ 84.692394] [<ffffffff812d4bf5>] page_fault+0x25/0x30
[ 84.692398] [<ffffffff810b02e4>] ? file_read_actor+0x3c/0x132
[ 84.692401] [<ffffffff810b0820>] ? __rcu_read_unlock+0x45/0x50
[ 84.692404] [<ffffffff810b2389>] generic_file_aio_read+0x364/0x5ba
[ 84.692424] [<ffffffffa022ae30>] ? xfs_ilock+0x49/0x7e [xfs]
[ 84.692442] [<ffffffffa024dfb3>] xfs_read+0x18d/0x1fa [xfs]
[ 84.692461] [<ffffffffa024a129>] xfs_file_aio_read+0x64/0x67 [xfs]
[ 84.692465] [<ffffffff810e8ac0>] do_sync_read+0xec/0x132
[ 84.692468] [<ffffffff8105ac3b>] ? autoremove_wake_function+0x0/0x3d
[ 84.692471] [<ffffffff810e9ba2>] ? __rcu_read_lock+0x0/0x3f
[ 84.692476] [<ffffffff81155ccc>] ? security_file_permission+0x16/0x18
[ 84.692479] [<ffffffff810e95ba>] vfs_read+0xad/0x107
[ 84.692482] [<ffffffff810e96e2>] sys_read+0x4c/0x75
[ 84.692485] [<ffffffff8102cfcf>] sysenter_dispatch+0x7/0x33
[ 84.692489] [<ffffffff812d3bfc>] ? trace_hardirqs_on_thunk+0x3a/0x3f

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