Messages in this thread | | | Date | Thu, 8 Sep 2022 18:54:44 +0800 | Subject | Re: [f2fs-dev] [PATCH] f2fs: fix missing mapping caused by the mount/umount race | From | Chao Yu <> |
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On 2022/8/31 11:05, Jaegeuk Kim wrote: > On 08/30, Jaegeuk Kim wrote: >> On 08/30, Chao Yu wrote: >>> 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(). >> >> I'm trying to dig further tho, it's not a bad inode, nor I_FREEING | I_CLEAR. >> It's very werid that thie meta inode is found in newly created superblock by >> the global hash table. I've checked that the same superblock pointer was used >> in the previous tests, but inode was evictied all the time. > > I'll drop this patch, since it turned out there is a bug in reiserfs which > doesn't free the root inode (ino=2). That leads f2fs to find an ino=2 with > the previous superblock point used by reiserfs. That stale inode has no valid > inode that f2fs can use. I tried to find where the root cause is in reiserfs, > but it seems quite hard to catch one. > > - reiserfs_fill_super > - reiserfs_xattr_init > - create_privroot > - xattr_mkdir > - reiserfs_new_inode > - reiserfs_get_unused_objectid returned 0 due to map crash > > It seems the error path doesn't handle the root inode properly.
Nice catch!
Could you please check:
f2fs: fix to detect obsolete inner inode during fill_super()
Thanks,
> >> >>> >>> 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; >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
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