Messages in this thread | | | Date | Sat, 17 Jan 2009 18:19:25 -0500 | From | Dave Jones <> | Subject | .29rc2 lockdep report. fb_mmap vs sys_mmap2 |
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Two mmaps enter! Fight!
======================================================= [ INFO: possible circular locking dependency detected ] 2.6.29-0.41.rc2.fc11.i686 #1 ------------------------------------------------------- plymouthd/669 is trying to acquire lock: (&fb_info->lock){--..}, at: [<c055355c>] fb_mmap+0x87/0x156
but task is already holding lock: (&mm->mmap_sem){----}, at: [<c0406a5d>] sys_mmap2+0x44/0x7b
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&mm->mmap_sem){----}: [<c044fef3>] __lock_acquire+0x9af/0xb22 [<c04500c1>] lock_acquire+0x5b/0x81 [<c048e036>] might_fault+0x60/0x80 [<c053dedc>] copy_to_user+0x2c/0xfc [<c05542cc>] fb_ioctl+0x247/0x338 [<c04b0c9f>] vfs_ioctl+0x22/0x69 [<c04b1214>] do_vfs_ioctl+0x46a/0x4a3 [<c04b128d>] sys_ioctl+0x40/0x5a [<c0403b76>] syscall_call+0x7/0xb [<ffffffff>] 0xffffffff
-> #0 (&fb_info->lock){--..}: [<c044fdc8>] __lock_acquire+0x884/0xb22 [<c04500c1>] lock_acquire+0x5b/0x81 [<c06e1b98>] __mutex_lock_common+0xd5/0x329 [<c06e1e84>] mutex_lock_nested+0x2e/0x36 [<c055355c>] fb_mmap+0x87/0x156 [<c0494620>] mmap_region+0x22b/0x43c [<c0494aa2>] do_mmap_pgoff+0x271/0x2d1 [<c0406a73>] sys_mmap2+0x5a/0x7b [<c0403b76>] syscall_call+0x7/0xb [<ffffffff>] 0xffffffff
other info that might help us debug this:
1 lock held by plymouthd/669: #0: (&mm->mmap_sem){----}, at: [<c0406a5d>] sys_mmap2+0x44/0x7b
stack backtrace: Pid: 669, comm: plymouthd Not tainted 2.6.29-0.41.rc2.fc11.i686 #1 Call Trace: [<c06e09b6>] ? printk+0xf/0x11 [<c044f32d>] print_circular_bug_tail+0x5d/0x68 [<c044fdc8>] __lock_acquire+0x884/0xb22 [<c04500c1>] lock_acquire+0x5b/0x81 [<c055355c>] ? fb_mmap+0x87/0x156 [<c06e1b98>] __mutex_lock_common+0xd5/0x329 [<c055355c>] ? fb_mmap+0x87/0x156 [<c06e1e84>] mutex_lock_nested+0x2e/0x36 [<c055355c>] ? fb_mmap+0x87/0x156 [<c055355c>] fb_mmap+0x87/0x156 [<c0494620>] mmap_region+0x22b/0x43c [<c0494aa2>] do_mmap_pgoff+0x271/0x2d1 [<c0406a73>] sys_mmap2+0x5a/0x7b [<c0403b76>] syscall_call+0x7/0xb
-- http://www.codemonkey.org.uk
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