Messages in this thread | | | Date | Tue, 30 Aug 2022 11:46:45 +0800 | Subject | Re: [f2fs-dev] [PATCH] f2fs: fix missing mapping caused by the mount/umount race | From | Chao Yu <> |
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On 2022/8/30 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; >
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