2.6.31.6: XFS DEBUG: Assertions cause kernel OOPS.

[Alex Elder]

Justin Piszcz wrote:
> Hi,
> 
> I wanted to compile my kernel with DEBUG for XFS and also kernel frame pointers
> to catch any issues.
> 
> However, DEBUG for XFS does more harm than good?

It should not.  This simple patch would improve things
but I'll add to my to-do list a review of assertions
to find and fix things of this type.

					-Alex

diff -Naur old/fs/xfs/xfs_bmap.c new/fs/xfs/xfs_bmap.c
--- old/fs/xfs/xfs_bmap.c       2009-11-30 07:55:59.000000000 -0600
+++ new/fs/xfs/xfs_bmap.c       2009-11-30 07:56:43.000000000 -0600
@@ -4843,6 +4843,7 @@
        orig_mval = mval;
        orig_nmap = *nmap;
 #endif
+       ASSERT(nmap != NULL);
        ASSERT(*nmap >= 1);
        ASSERT(*nmap <= XFS_BMAP_MAX_NMAP || !(flags & XFS_BMAPI_WRITE));
        whichfork = (flags & XFS_BMAPI_ATTRFORK) ?


> I tried to install bonnie++:
> # apt-get install -y bonnie++
> 
> And then this happened:
> 
> [ 1578.768558] Assertion failed: *nmap >= 1, file: fs/xfs/xfs_bmap.c, line: 4846
> [ 1578.768633] ------------[ cut here ]------------
> [ 1578.768690] kernel BUG at fs/xfs/support/debug.c:109!
> [ 1578.768742] invalid opcode: 0000 [#1] SMP
> [ 1578.768839] last sysfs file:
> /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/host15/target15:0:0/15:0:0:0/queue_depth [
> 1578.768939] CPU 1 [ 1578.769016] Pid: 3273, comm: dpkg Not tainted 2.6.31.6 #6
> [ 1578.769083] RIP: 0010:[<ffffffff81243ada>]  [<ffffffff81243ada>] assfail+0x1a/0x20
> [ 1578.769203] RSP: 0018:ffff880121d4bc08  EFLAGS: 00010296
> [ 1578.769252] RAX: 0000000000000054 RBX: 0000000000000000 RCX: ffffffff81364fb0
> [ 1578.769252] RDX: ffff880028038000 RSI: 0000000000000046 RDI: ffffffff816b4730
> [ 1578.769252] RBP: ffff880121d4bc08 R08: 0000000000000000 R09: 0000000000000006
> [ 1578.769252] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000800000000
> [ 1578.769252] R13: ffff88012a295580 R14: 0000000000000002 R15: ffff88012a522000
> [ 1578.769252] FS:  00007f2a7367d790(0000) GS:ffff880028038000(0000) knlGS:0000000000000000
> [ 1578.769252] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1578.769252] CR2: 000000000204e000 CR3: 0000000121d53000 CR4: 00000000000026e0
> [ 1578.769252] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 1578.769252] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 1578.769252] Process dpkg (pid: 3273, threadinfo ffff880121d4a000, task ffff88012b98b990)
> [ 1578.769252] Stack:
> [ 1578.769252]  ffff880121d4bdb8 ffffffff811eb916 0000000121d4bc38 000000000204e000
> [ 1578.769252] <0> ffff8801244a85d0 0000000000000286 ffff880121d4bc68 ffffffff81260c51
> [ 1578.769252] <0> ffff880121d4bc68 0000000000000000 000000080204e000 00000000007ffff8
> [ 1578.769252] Call Trace:
> [ 1578.769252]  [<ffffffff811eb916>] xfs_bmapi+0x66/0x1940
> [ 1578.769252]  [<ffffffff81260c51>] ? __up_read+0x91/0xb0
> [ 1578.769252]  [<ffffffff8123a0a7>] ? xfs_buf_free+0xc7/0x110
> [ 1578.769252]  [<ffffffff8123a1e6>] ? xfs_buf_rele+0xf6/0x130
> [ 1578.769252]  [<ffffffff8122e70a>] ? xfs_trans_brelse+0x19a/0x2a0
> [ 1578.769252]  [<ffffffff811f7ac7>] ? xfs_da_brelse+0x77/0x120
> [ 1578.769252]  [<ffffffff810bf63d>] ? filldir+0x9d/0xe0
> [ 1578.769252]  [<ffffffff8120225a>] xfs_dir2_leaf_getdents+0x61a/0x780
> [ 1578.769252]  [<ffffffff810bf5a0>] ? filldir+0x0/0xe0
> [ 1578.769252]  [<ffffffff810bf5a0>] ? filldir+0x0/0xe0
> [ 1578.769252]  [<ffffffff811fc6ec>] xfs_readdir+0x10c/0x110
> [ 1578.769252]  [<ffffffff810bf5a0>] ? filldir+0x0/0xe0
> [ 1578.769252]  [<ffffffff8123b4f4>] xfs_file_readdir+0x34/0x50
> [ 1578.769252]  [<ffffffff810bf7f8>] vfs_readdir+0xa8/0xc0
> [ 1578.769252]  [<ffffffff810bf963>] sys_getdents+0x83/0xe0
> [ 1578.769252]  [<ffffffff8102d1ab>] system_call_fastpath+0x16/0x1b
> [ 1578.769252] Code: 57 81 48 c7 c7 8e 94 57 81 e8 b3 19 02 00 c9 c3 90 55 89 d1 48 89 e5 48 89
> f2 31 c0 48 89 fe 48 c7 c7 f0 d0 59 81 e8 15 6a 25 00 <0f> 0b eb fe 66 90 55 48 89 e5 41 57 41
> 56 49 89 ce 41 55 49 89 [ 1578.773074] RIP  [<ffffffff81243ada>] assfail+0x1a/0x20 [
> 1578.773074]  RSP <ffff880121d4bc08> [ 1578.773343] ---[ end trace 00b4a182e72dfb60 ]---
> 
> Will recompile without XFS DEBUG but FYI.
> 
> Justin.
> 
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