mirror of
https://github.com/torvalds/linux.git
synced 2024-11-16 09:02:00 +00:00
cf6f54e3f1
Fixes the following lockdep splat: [ 1.244527] ============================================= [ 1.245193] [ INFO: possible recursive locking detected ] [ 1.245193] 4.2.0-rc1+ #37 Not tainted [ 1.245193] --------------------------------------------- [ 1.245193] cp/742 is trying to acquire lock: [ 1.245193] (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff812b3f69>] ubifs_init_security+0x29/0xb0 [ 1.245193] [ 1.245193] but task is already holding lock: [ 1.245193] (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff81198e7f>] path_openat+0x3af/0x1280 [ 1.245193] [ 1.245193] other info that might help us debug this: [ 1.245193] Possible unsafe locking scenario: [ 1.245193] [ 1.245193] CPU0 [ 1.245193] ---- [ 1.245193] lock(&sb->s_type->i_mutex_key#9); [ 1.245193] lock(&sb->s_type->i_mutex_key#9); [ 1.245193] [ 1.245193] *** DEADLOCK *** [ 1.245193] [ 1.245193] May be due to missing lock nesting notation [ 1.245193] [ 1.245193] 2 locks held by cp/742: [ 1.245193] #0: (sb_writers#5){.+.+.+}, at: [<ffffffff811ad37f>] mnt_want_write+0x1f/0x50 [ 1.245193] #1: (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff81198e7f>] path_openat+0x3af/0x1280 [ 1.245193] [ 1.245193] stack backtrace: [ 1.245193] CPU: 2 PID: 742 Comm: cp Not tainted 4.2.0-rc1+ #37 [ 1.245193] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140816_022509-build35 04/01/2014 [ 1.245193] ffffffff8252d530 ffff88007b023a38 ffffffff814f6f49 ffffffff810b56c5 [ 1.245193] ffff88007c30cc80 ffff88007b023af8 ffffffff810a150d ffff88007b023a68 [ 1.245193] 000000008101302a ffff880000000000 00000008f447e23f ffffffff8252d500 [ 1.245193] Call Trace: [ 1.245193] [<ffffffff814f6f49>] dump_stack+0x4c/0x65 [ 1.245193] [<ffffffff810b56c5>] ? console_unlock+0x1c5/0x510 [ 1.245193] [<ffffffff810a150d>] __lock_acquire+0x1a6d/0x1ea0 [ 1.245193] [<ffffffff8109fa78>] ? __lock_is_held+0x58/0x80 [ 1.245193] [<ffffffff810a1a93>] lock_acquire+0xd3/0x270 [ 1.245193] [<ffffffff812b3f69>] ? ubifs_init_security+0x29/0xb0 [ 1.245193] [<ffffffff814fc83b>] mutex_lock_nested+0x6b/0x3a0 [ 1.245193] [<ffffffff812b3f69>] ? ubifs_init_security+0x29/0xb0 [ 1.245193] [<ffffffff812b3f69>] ? ubifs_init_security+0x29/0xb0 [ 1.245193] [<ffffffff812b3f69>] ubifs_init_security+0x29/0xb0 [ 1.245193] [<ffffffff8128e286>] ubifs_create+0xa6/0x1f0 [ 1.245193] [<ffffffff81198e7f>] ? path_openat+0x3af/0x1280 [ 1.245193] [<ffffffff81195d15>] vfs_create+0x95/0xc0 [ 1.245193] [<ffffffff8119929c>] path_openat+0x7cc/0x1280 [ 1.245193] [<ffffffff8109ffe3>] ? __lock_acquire+0x543/0x1ea0 [ 1.245193] [<ffffffff81088f20>] ? sched_clock_cpu+0x90/0xc0 [ 1.245193] [<ffffffff81088c00>] ? calc_global_load_tick+0x60/0x90 [ 1.245193] [<ffffffff81088f20>] ? sched_clock_cpu+0x90/0xc0 [ 1.245193] [<ffffffff811a9cef>] ? __alloc_fd+0xaf/0x180 [ 1.245193] [<ffffffff8119ac55>] do_filp_open+0x75/0xd0 [ 1.245193] [<ffffffff814ffd86>] ? _raw_spin_unlock+0x26/0x40 [ 1.245193] [<ffffffff811a9cef>] ? __alloc_fd+0xaf/0x180 [ 1.245193] [<ffffffff81189bd9>] do_sys_open+0x129/0x200 [ 1.245193] [<ffffffff81189cc9>] SyS_open+0x19/0x20 [ 1.245193] [<ffffffff81500717>] entry_SYSCALL_64_fastpath+0x12/0x6f While the lockdep splat is a false positive, becuase path_openat holds i_mutex of the parent directory and ubifs_init_security() tries to acquire i_mutex of a new inode, it reveals that taking i_mutex in ubifs_init_security() is in vain because it is only being called in the inode allocation path and therefore nobody else can see the inode yet. Cc: stable@vger.kernel.org # 3.20- Reported-and-tested-by: Boris Brezillon <boris.brezillon@free-electrons.com> Reviewed-and-tested-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: dedekind1@gmail.com |
||
|---|---|---|
| .. | ||
| budget.c | ||
| commit.c | ||
| compress.c | ||
| debug.c | ||
| debug.h | ||
| dir.c | ||
| file.c | ||
| find.c | ||
| gc.c | ||
| io.c | ||
| ioctl.c | ||
| journal.c | ||
| Kconfig | ||
| key.h | ||
| log.c | ||
| lprops.c | ||
| lpt_commit.c | ||
| lpt.c | ||
| Makefile | ||
| master.c | ||
| misc.h | ||
| orphan.c | ||
| recovery.c | ||
| replay.c | ||
| sb.c | ||
| scan.c | ||
| shrinker.c | ||
| super.c | ||
| tnc_commit.c | ||
| tnc_misc.c | ||
| tnc.c | ||
| ubifs-media.h | ||
| ubifs.h | ||
| xattr.c | ||