在 2023/3/25 3:42, Andrew Morton 写道:
On Fri, 24 Mar 2023 10:28:00 +0000 Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> wrote:
XFS allows CoW on non-shared extents to combat fragmentation[1]. The
old non-shared extent could be mwrited before, its dax entry is marked
dirty. To be able to delete this entry, clear its dirty mark before
invalidate_inode_pages2_range().
What are the user-visible runtime effects of this flaw?
This bug won't leak or mess up the data of filesystem. In dmesg it will
show like this:
[ 28.512349] ------------[ cut here ]------------
[ 28.512622] WARNING: CPU: 2 PID: 5255 at fs/dax.c:390
dax_insert_entry+0x342/0x390
[ 28.513050] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 nfs
lockd grace fscache netfs nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib
nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct
nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables
[ 28.515462] CPU: 2 PID: 5255 Comm: fsstress Kdump: loaded Not tainted
6.3.0-rc1-00001-g85e1481e19c1-dirty #117
[ 28.515902] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
Arch Linux 1.16.1-1-1 04/01/2014
[ 28.516307] RIP: 0010:dax_insert_entry+0x342/0x390
[ 28.516536] Code: 30 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48
8b 45 20 48 83 c0 01 e9 e2 fe ff ff 48 8b 45 20 48 83 c0 01 e9 cd fe ff
ff <0f> 0b e9 53 ff ff ff 48 8b 7c 24 08 31 f6 e8 1b 61 a1 00 eb 8c 48
[ 28.517417] RSP: 0000:ffffc9000845fb18 EFLAGS: 00010086
[ 28.517721] RAX: 0000000000000053 RBX: 0000000000000155 RCX:
000000000018824b
[ 28.518113] RDX: 0000000000000000 RSI: ffffffff827525a6 RDI:
00000000ffffffff
[ 28.518515] RBP: ffffea00062092c0 R08: 0000000000000000 R09:
ffffc9000845f9c8
[ 28.518905] R10: 0000000000000003 R11: ffffffff82ddb7e8 R12:
0000000000000155
[ 28.519301] R13: 0000000000000000 R14: 000000000018824b R15:
ffff88810cfa76b8
[ 28.519703] FS: 00007f14a0c94740(0000) GS:ffff88817bd00000(0000)
knlGS:0000000000000000
[ 28.520148] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 28.520472] CR2: 00007f14a0c8d000 CR3: 000000010321c004 CR4:
0000000000770ee0
[ 28.520863] PKRU: 55555554
[ 28.521043] Call Trace:
[ 28.521219] <TASK>
[ 28.521368] dax_fault_iter+0x196/0x390
[ 28.521595] dax_iomap_pte_fault+0x19b/0x3d0
[ 28.521852] __xfs_filemap_fault+0x234/0x2b0
[ 28.522116] __do_fault+0x30/0x130
[ 28.522334] do_fault+0x193/0x340
[ 28.522586] __handle_mm_fault+0x2d3/0x690
[ 28.522975] handle_mm_fault+0xe6/0x2c0
[ 28.523259] do_user_addr_fault+0x1bc/0x6f0
[ 28.523521] exc_page_fault+0x60/0x140
[ 28.523763] asm_exc_page_fault+0x22/0x30
[ 28.524001] RIP: 0033:0x7f14a0b589ca
[ 28.524225] Code: c5 fe 7f 07 c5 fe 7f 47 20 c5 fe 7f 47 40 c5 fe 7f
47 60 c5 f8 77 c3 66 0f 1f 84 00 00 00 00 00 40 0f b6 c6 48 89 d1 48 89
fa <f3> aa 48 89 d0 c5 f8 77 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90
[ 28.525198] RSP: 002b:00007fff1dea1c98 EFLAGS: 00010202
[ 28.525505] RAX: 000000000000001e RBX: 000000000014a000 RCX:
0000000000006046
[ 28.525895] RDX: 00007f14a0c82000 RSI: 000000000000001e RDI:
00007f14a0c8d000
[ 28.526290] RBP: 000000000000006f R08: 0000000000000004 R09:
000000000014a000
[ 28.526681] R10: 0000000000000008 R11: 0000000000000246 R12:
028f5c28f5c28f5c
[ 28.527067] R13: 8f5c28f5c28f5c29 R14: 0000000000011046 R15:
00007f14a0c946c0
[ 28.527449] </TASK>
[ 28.527600] ---[ end trace 0000000000000000 ]---
>
> Are we able to identify a Fixes: target for this? Perhaps
> f80e1668888f3 ("fsdax: invalidate pages when CoW")?
>
Yes, it is to fix this commit.
--
Thanks,
Ruan.
