| From b45d71fb89ab8adfe727b9d0ee188ed58582a647 Mon Sep 17 00:00:00 2001 |
| From: "Joel Fernandes (Google)" <joel@joelfernandes.org> |
| Date: Thu, 20 Sep 2018 12:22:39 -0700 |
| Subject: mm: shmem.c: Correctly annotate new inodes for lockdep |
| |
| From: Joel Fernandes (Google) <joel@joelfernandes.org> |
| |
| commit b45d71fb89ab8adfe727b9d0ee188ed58582a647 upstream. |
| |
| 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 |
| |
| Link: http://lkml.kernel.org/r/20180821231835.166639-1-joel@joelfernandes.org |
| Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> |
| Reported-by: syzbot <syzkaller@googlegroups.com> |
| Reviewed-by: NeilBrown <neilb@suse.com> |
| Suggested-by: NeilBrown <neilb@suse.com> |
| Cc: Matthew Wilcox <willy@infradead.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Hugh Dickins <hughd@google.com> |
| Cc: <stable@vger.kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/shmem.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/mm/shmem.c |
| +++ b/mm/shmem.c |
| @@ -2207,6 +2207,8 @@ static struct inode *shmem_get_inode(str |
| mpol_shared_policy_init(&info->policy, NULL); |
| break; |
| } |
| + |
| + lockdep_annotate_inode_mutex_key(inode); |
| } else |
| shmem_free_inode(sb); |
| return inode; |