Jeff, On Tue, Jul 16, 2013 at 01:11:16PM +0800, Jeff Liu wrote: > From: Jie Liu <jeff.liu@xxxxxxxxxx> > > In xfs_vm_write_failed(), we evaluate the block_offset of pos with > PAGE_MASK which is an unsigned long. That is fine on 64-bit platforms > regardless of whether the request pos is 32-bit or 64-bit. However, on > 32-bit platforms the value is 0xfffff000 and so the high 32 bits in it > will be masked off with (pos & PAGE_MASK) for a 64-bit pos. > > As a result, the evaluated block_offset is incorrect which will cause > this failure ASSERT(block_offset + from == pos); and potentially pass > the wrong block to xfs_vm_kill_delalloc_range(). > > In this case, we can get a kernel panic if CONFIG_XFS_DEBUG is enabled: > > XFS: Assertion failed: block_offset + from == pos, file: fs/xfs/xfs_aops.c, line: 1504 > > ------------[ cut here ]------------ > kernel BUG at fs/xfs/xfs_message.c:100! > invalid opcode: 0000 [#1] SMP > ........ > Pid: 4057, comm: mkfs.xfs Tainted: G O 3.9.0-rc2 #1 > EIP: 0060:[<f94a7e8b>] EFLAGS: 00010282 CPU: 0 > EIP is at assfail+0x2b/0x30 [xfs] > EAX: 00000056 EBX: f6ef28a0 ECX: 00000007 EDX: f57d22a4 > ESI: 1c2fb000 EDI: 00000000 EBP: ea6b5d30 ESP: ea6b5d1c > DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 > CR0: 8005003b CR2: 094f3ff4 CR3: 2bcb4000 CR4: 000006f0 > DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > DR6: ffff0ff0 DR7: 00000400 > Process mkfs.xfs (pid: 4057, ti=ea6b4000 task=ea5799e0 task.ti=ea6b4000) > Stack: > 00000000 f9525c48 f951fa80 f951f96b 000005e4 ea6b5d7c f9494b34 c19b0ea2 > 00000066 f3d6c620 c19b0ea2 00000000 e9a91458 00001000 00000000 00000000 > 00000000 c15c7e89 00000000 1c2fb000 00000000 00000000 1c2fb000 00000080 > Call Trace: > [<f9494b34>] xfs_vm_write_failed+0x74/0x1b0 [xfs] > [<c15c7e89>] ? printk+0x4d/0x4f > [<f9494d7d>] xfs_vm_write_begin+0x10d/0x170 [xfs] > [<c110a34c>] generic_file_buffered_write+0xdc/0x210 > [<f949b669>] xfs_file_buffered_aio_write+0xf9/0x190 [xfs] > [<f949b7f3>] xfs_file_aio_write+0xf3/0x160 [xfs] > [<c115e504>] do_sync_write+0x94/0xd0 > [<c115ed1f>] vfs_write+0x8f/0x160 > [<c115e470>] ? wait_on_retry_sync_kiocb+0x50/0x50 > [<c115f017>] sys_write+0x47/0x80 > [<c15d860d>] sysenter_do_call+0x12/0x28 > ............. > EIP: [<f94a7e8b>] assfail+0x2b/0x30 [xfs] SS:ESP 0068:ea6b5d1c > ---[ end trace cdd9af4f4ecab42f ]--- > Kernel panic - not syncing: Fatal exception > > In order to avoid this, we can evaluate the block_offset of the start > of the page by using shifts rather than masks the mismatch problem. > > Thanks Dave Chinner for help finding and fixing this bug. > > Reported-by: Michael L. Semon <mlsemon35@xxxxxxxxx> > Reviewed-by: Dave Chinner <david@xxxxxxxxxxxxx> > Reviewed-by: Mark Tinguely <tinguely@xxxxxxx> > Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx> Applied. Thanks, Ben _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
