[PATCH] nilfs2: fix oops due to a bad aops initialization
From: Ryusuke Konishi
Date: Wed Mar 30 2011 - 00:26:25 EST
I've found a regression of nilfs2 file system in 2.6.39-rc1.
The recent per-queue plugging removal patch causes kernel oopses in
nilfs. The following patch will fix this.
I'll send it to Linus along with other bug-fixes.
Thanks,
Ryusuke Konishi
--
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
nilfs2: fix oops due to a bad aops initialization
Nilfs in 2.6.39-rc1 hit the following oops:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
IP: [<ffffffff810ac235>] try_to_release_page+0x2a/0x3d
PGD 234cb6067 PUD 234c72067 PMD 0
Oops: 0000 [#1] SMP
<snip>
Process truncate (pid: 10995, threadinfo ffff8802353c2000, task ffff880234cfa000)
Stack:
ffff8802333c77b8 ffffffff810b64b0 0000000000003802 ffffffffa0052cca
0000000000000000 ffff8802353c3b58 0000000000000000 ffff8802353c3b58
0000000000000001 0000000000000000 ffffea0007b92308 ffffea0007b92308
Call Trace:
[<ffffffff810b64b0>] ? invalidate_inode_pages2_range+0x15f/0x273
[<ffffffffa0052cca>] ? nilfs_palloc_get_block+0x2d/0xaf [nilfs2]
[<ffffffff810589e7>] ? bit_waitqueue+0x14/0xa1
[<ffffffff81058ab1>] ? wake_up_bit+0x10/0x20
[<ffffffffa00433fd>] ? nilfs_forget_buffer+0x66/0x7a [nilfs2]
[<ffffffffa00467b8>] ? nilfs_btree_concat_left+0x5c/0x77 [nilfs2]
[<ffffffffa00471fc>] ? nilfs_btree_delete+0x395/0x3cf [nilfs2]
[<ffffffffa00449a3>] ? nilfs_bmap_do_delete+0x6e/0x79 [nilfs2]
[<ffffffffa0045845>] ? nilfs_btree_last_key+0x14b/0x15e [nilfs2]
[<ffffffffa00449dd>] ? nilfs_bmap_truncate+0x2f/0x83 [nilfs2]
[<ffffffffa0044ab2>] ? nilfs_bmap_last_key+0x35/0x62 [nilfs2]
[<ffffffffa003e99b>] ? nilfs_truncate_bmap+0x6b/0xc7 [nilfs2]
[<ffffffffa003ee4a>] ? nilfs_truncate+0x79/0xe4 [nilfs2]
[<ffffffff810b6c00>] ? vmtruncate+0x33/0x3b
[<ffffffffa003e8f1>] ? nilfs_setattr+0x4d/0x8c [nilfs2]
[<ffffffff81026106>] ? do_page_fault+0x31b/0x356
[<ffffffff810f9d61>] ? notify_change+0x17d/0x262
[<ffffffff810e5046>] ? do_truncate+0x65/0x80
[<ffffffff810e52af>] ? sys_ftruncate+0xf1/0xf6
[<ffffffff8132c012>] ? system_call_fastpath+0x16/0x1b
Code: c3 48 83 ec 08 48 8b 17 48 8b 47 18 80 e2 01 75 04 0f 0b eb fe 48 8b 17 80 e6 20 74 05 31 c0 41 59 c3 48 85 c0 74 11 48 8b 40 58
8b 40 48 48 85 c0 74 04 41 58 ff e0 59 e9 b1 b5 05 00 41 54
RIP [<ffffffff810ac235>] try_to_release_page+0x2a/0x3d
RSP <ffff8802353c3b08>
CR2: 0000000000000048
This oops was brought in by the change "block: remove per-queue
plugging" (commit: 7eaceaccab5f40bb). It initializes mapping->a_ops
with a NULL pointer for some pages in nilfs (e.g. btree node pages),
but mm code doesn't NULL pointer checks against mapping->a_ops. (the
check is done for each callback function)
This corrects the aops initialization and fixes the oops.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Cc: Jens Axboe <jaxboe@xxxxxxxxxxxx>
---
fs/nilfs2/page.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index 4d2a1ee..9d2dc6b 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -495,12 +495,14 @@ unsigned nilfs_page_count_clean_buffers(struct page *page,
void nilfs_mapping_init(struct address_space *mapping,
struct backing_dev_info *bdi)
{
+ static const struct address_space_operations empty_aops;
+
mapping->host = NULL;
mapping->flags = 0;
mapping_set_gfp_mask(mapping, GFP_NOFS);
mapping->assoc_mapping = NULL;
mapping->backing_dev_info = bdi;
- mapping->a_ops = NULL;
+ mapping->a_ops = &empty_aops;
}
/*
--
1.7.3.5
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