lkml.org 
[lkml]   [2022]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [f2fs-dev] [PATCH] f2fs: fix missing mapping caused by the mount/umount race
From
On 2022/8/30 5:52, Jaegeuk Kim wrote:
> Sometimes we can get a cached meta_inode which has no aops yet. Let's set it
> all the time to fix the below panic.
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> Mem abort info:
> ESR = 0x0000000086000004
> EC = 0x21: IABT (current EL), IL = 32 bits
> SET = 0, FnV = 0
> EA = 0, S1PTW = 0
> FSC = 0x04: level 0 translation fault
> user pgtable: 4k pages, 48-bit VAs, pgdp=0000000109ee4000
> [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
> Internal error: Oops: 86000004 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 1 PID: 3045 Comm: syz-executor330 Not tainted 6.0.0-rc2-syzkaller-16455-ga41a877bc12d #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
> pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : 0x0
> lr : folio_mark_dirty+0xbc/0x208 mm/page-writeback.c:2748
> sp : ffff800012783970
> x29: ffff800012783970 x28: 0000000000000000 x27: ffff800012783b08
> x26: 0000000000000001 x25: 0000000000000400 x24: 0000000000000001
> x23: ffff0000c736e000 x22: 0000000000000045 x21: 05ffc00000000015
> x20: ffff0000ca7403b8 x19: fffffc00032ec600 x18: 0000000000000181
> x17: ffff80000c04d6bc x16: ffff80000dbb8658 x15: 0000000000000000
> x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> x11: ff808000083e9814 x10: 0000000000000000 x9 : ffff8000083e9814
> x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
> x5 : ffff0000cbb19000 x4 : ffff0000cb3d2000 x3 : ffff0000cbb18f80
> x2 : fffffffffffffff0 x1 : fffffc00032ec600 x0 : ffff0000ca7403b8
> Call trace:
> 0x0
> set_page_dirty+0x38/0xbc mm/folio-compat.c:62
> f2fs_update_meta_page+0x80/0xa8 fs/f2fs/segment.c:2369
> do_checkpoint+0x794/0xea8 fs/f2fs/checkpoint.c:1522
> f2fs_write_checkpoint+0x3b8/0x568 fs/f2fs/checkpoint.c:1679
>
> Cc: stable@vger.kernel.org
> Reported-by: syzbot+775a3440817f74fddb8c@syzkaller.appspotmail.com
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
> fs/f2fs/inode.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index 6d11c365d7b4..1feb0a8a699e 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -490,10 +490,7 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> if (!inode)
> return ERR_PTR(-ENOMEM);
>
> - if (!(inode->i_state & I_NEW)) {
> - trace_f2fs_iget(inode);
> - return inode;
> - }
> + /* We can see an old cached inode. Let's set the aops all the time. */

Why an old cached inode (has no I_NEW flag) has NULL a_ops pointer? If it is a bad
inode, it should be unhashed before unlock_new_inode().

Thanks,

> if (ino == F2FS_NODE_INO(sbi) || ino == F2FS_META_INO(sbi))
> goto make_now;
>
> @@ -502,6 +499,11 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> goto make_now;
> #endif
>
> + if (!(inode->i_state & I_NEW)) {
> + trace_f2fs_iget(inode);
> + return inode;
> + }
> +
> ret = do_read_inode(inode);
> if (ret)
> goto bad_inode;
> @@ -557,7 +559,8 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> file_dont_truncate(inode);
> }
>
> - unlock_new_inode(inode);
> + if (inode->i_state & I_NEW)
> + unlock_new_inode(inode);
> trace_f2fs_iget(inode);
> return inode;
>

\
 
 \ /
  Last update: 2022-08-30 05:47    [W:0.061 / U:0.348 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site