| Message ID | 20180814161652.28831-1-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: shmem: Correctly annotate new inodes | expand |
On Tue, Aug 14 2018, Joel Fernandes (Google) wrote: > Directories and inodes don't necessarily need to be in the same > lockdep class. For ex, hugetlbfs splits them out too to prevent > false positives in lockdep. Annotate correctly after new inode > creation. If its a directory inode, it will be put into a different > class. > > This should fix a lockdep splat reported by syzbot: > >> ====================================================== >> WARNING: possible circular locking dependency detected >> 4.18.0-rc8-next-20180810+ #36 Not tainted >> ------------------------------------------------------ >> syz-executor900/4483 is trying to acquire lock: >> 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: inode_lock >> include/linux/fs.h:765 [inline] >> 00000000d2bfc8fe (&sb->s_type->i_mutex_key#9){++++}, at: >> shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 >> >> but task is already holding lock: >> 0000000025208078 (ashmem_mutex){+.+.}, at: ashmem_shrink_scan+0xb4/0x630 >> drivers/staging/android/ashmem.c:448 >> >> which lock already depends on the new lock. >> >> -> #2 (ashmem_mutex){+.+.}: >> __mutex_lock_common kernel/locking/mutex.c:925 [inline] >> __mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073 >> mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088 >> ashmem_mmap+0x55/0x520 drivers/staging/android/ashmem.c:361 >> call_mmap include/linux/fs.h:1844 [inline] >> mmap_region+0xf27/0x1c50 mm/mmap.c:1762 >> do_mmap+0xa10/0x1220 mm/mmap.c:1535 >> do_mmap_pgoff include/linux/mm.h:2298 [inline] >> vm_mmap_pgoff+0x213/0x2c0 mm/util.c:357 >> ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585 >> __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] >> __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] >> __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 >> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> -> #1 (&mm->mmap_sem){++++}: >> __might_fault+0x155/0x1e0 mm/memory.c:4568 >> _copy_to_user+0x30/0x110 lib/usercopy.c:25 >> copy_to_user include/linux/uaccess.h:155 [inline] >> filldir+0x1ea/0x3a0 fs/readdir.c:196 >> dir_emit_dot include/linux/fs.h:3464 [inline] >> dir_emit_dots include/linux/fs.h:3475 [inline] >> dcache_readdir+0x13a/0x620 fs/libfs.c:193 >> iterate_dir+0x48b/0x5d0 fs/readdir.c:51 >> __do_sys_getdents fs/readdir.c:231 [inline] >> __se_sys_getdents fs/readdir.c:212 [inline] >> __x64_sys_getdents+0x29f/0x510 fs/readdir.c:212 >> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> -> #0 (&sb->s_type->i_mutex_key#9){++++}: >> lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924 >> down_write+0x8f/0x130 kernel/locking/rwsem.c:70 >> inode_lock include/linux/fs.h:765 [inline] >> shmem_fallocate+0x18b/0x12e0 mm/shmem.c:2602 >> ashmem_shrink_scan+0x236/0x630 drivers/staging/android/ashmem.c:455 >> ashmem_ioctl+0x3ae/0x13a0 drivers/staging/android/ashmem.c:797 >> vfs_ioctl fs/ioctl.c:46 [inline] >> file_ioctl fs/ioctl.c:501 [inline] >> do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 >> ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 >> __do_sys_ioctl fs/ioctl.c:709 [inline] >> __se_sys_ioctl fs/ioctl.c:707 [inline] >> __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 >> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> other info that might help us debug this: >> >> Chain exists of: >> &sb->s_type->i_mutex_key#9 --> &mm->mmap_sem --> ashmem_mutex >> >> Possible unsafe locking scenario: >> >> CPU0 CPU1 >> ---- ---- >> lock(ashmem_mutex); >> lock(&mm->mmap_sem); >> lock(ashmem_mutex); >> lock(&sb->s_type->i_mutex_key#9); >> >> *** DEADLOCK *** >> >> 1 lock held by syz-executor900/4483: >> #0: 0000000025208078 (ashmem_mutex){+.+.}, at: >> ashmem_shrink_scan+0xb4/0x630 drivers/staging/android/ashmem.c:448 > > Reported-by: syzbot <syzkaller@googlegroups.com> > Cc: willy@infradead.org > Cc: stable@vger.kernel.org > Cc: peterz@infradead.org > Suggested-by: Neil Brown <neilb@suse.com> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: NeilBrown <neilb@suse.com> This is necessary for any filesystem that doesn't use unlock_new_inode(). (If/when you repost, I suggest including Andrew Morton). Thanks, NeilBrown > --- > mm/shmem.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 2cab84403055..4429a8fd932d 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -2225,6 +2225,8 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode > mpol_shared_policy_init(&info->policy, NULL); > break; > } > + > + lockdep_annotate_inode_mutex_key(inode); > } else > shmem_free_inode(sb); > return inode; > -- > 2.18.0.597.ga71716f1ad-goog
diff --git a/mm/shmem.c b/mm/shmem.c index 2cab84403055..4429a8fd932d 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2225,6 +2225,8 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode mpol_shared_policy_init(&info->policy, NULL); break; } + + lockdep_annotate_inode_mutex_key(inode); } else shmem_free_inode(sb); return inode;