Subject: [merged] hugetlb-fix-lockdep-splat-caused-by-pmd-sharing.patch removed from -mm tree To: mhocko@xxxxxxx,davej@xxxxxxxxxx,minchan@xxxxxxxxxx,peterz@xxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 14 Aug 2013 12:35:36 -0700 The patch titled Subject: hugetlb: fix lockdep splat caused by pmd sharing has been removed from the -mm tree. Its filename was hugetlb-fix-lockdep-splat-caused-by-pmd-sharing.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Michal Hocko <mhocko@xxxxxxx> Subject: hugetlb: fix lockdep splat caused by pmd sharing Dave has reported the following lockdep splat: [128095.470960] ================================= [128095.471315] [ INFO: inconsistent lock state ] [128095.471660] 3.11.0-rc1+ #9 Not tainted [128095.472156] --------------------------------- [128095.472905] inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage. [128095.473650] kswapd0/49 [HC0[0]:SC0[0]:HE1:SE1] takes: [128095.474373] (&mapping->i_mmap_mutex){+.+.?.}, at: [<c114971b>] page_referenced+0x87/0x5e3 [128095.475128] {RECLAIM_FS-ON-W} state was registered at: [128095.475866] [<c10a6232>] mark_held_locks+0x81/0xe7 [128095.476597] [<c10a8db3>] lockdep_trace_alloc+0x5e/0xbc [128095.477322] [<c112316b>] __alloc_pages_nodemask+0x8b/0x9b6 [128095.478049] [<c1123ab6>] __get_free_pages+0x20/0x31 [128095.478769] [<c1123ad9>] get_zeroed_page+0x12/0x14 [128095.479477] [<c113fe1e>] __pmd_alloc+0x1c/0x6b [128095.480138] [<c1155ea7>] huge_pmd_share+0x265/0x283 [128095.480138] [<c1155f22>] huge_pte_alloc+0x5d/0x71 [128095.480138] [<c115612e>] hugetlb_fault+0x7c/0x64a [128095.480138] [<c114087c>] handle_mm_fault+0x255/0x299 [128095.480138] [<c15bbab0>] __do_page_fault+0x142/0x55c [128095.480138] [<c15bbed7>] do_page_fault+0xd/0x16 [128095.480138] [<c15b927c>] error_code+0x6c/0x74 [128095.480138] irq event stamp: 3136917 [128095.480138] hardirqs last enabled at (3136917): [<c15b8139>] _raw_spin_unlock_irq+0x27/0x50 [128095.480138] hardirqs last disabled at (3136916): [<c15b7f4e>] _raw_spin_lock_irq+0x15/0x78 [128095.480138] softirqs last enabled at (3136180): [<c1048e4a>] __do_softirq+0x137/0x30f [128095.480138] softirqs last disabled at (3136175): [<c1049195>] irq_exit+0xa8/0xaa [128095.480138] other info that might help us debug this: [128095.480138] Possible unsafe locking scenario: [128095.480138] CPU0 [128095.480138] ---- [128095.480138] lock(&mapping->i_mmap_mutex); [128095.480138] <Interrupt> [128095.480138] lock(&mapping->i_mmap_mutex); [128095.480138] *** DEADLOCK *** [128095.480138] no locks held by kswapd0/49. [128095.480138] stack backtrace: [128095.480138] CPU: 1 PID: 49 Comm: kswapd0 Not tainted 3.11.0-rc1+ #9 [128095.480138] Hardware name: Dell Inc. Precision WorkStation 490 /0DT031, BIOS A08 04/25/2008 [128095.480138] c1d32630 00000000 ee39fb18 c15b001e ee395780 ee39fb54 c15acdcb c1751845 [128095.480138] c1751bbf 00000031 00000000 00000000 00000000 00000000 00000001 00000001 [128095.480138] c1751bbf 00000008 ee395c44 00000100 ee39fb88 c10a6130 00000008 0000d8fb [128095.480138] Call Trace: [128095.480138] [<c15b001e>] dump_stack+0x4b/0x79 [128095.480138] [<c15acdcb>] print_usage_bug+0x1d9/0x1e3 [128095.480138] [<c10a6130>] mark_lock+0x1e0/0x261 [128095.480138] [<c10a5878>] ? check_usage_backwards+0x109/0x109 [128095.480138] [<c10a6cde>] __lock_acquire+0x623/0x17f2 [128095.480138] [<c107aa43>] ? sched_clock_cpu+0xcd/0x130 [128095.480138] [<c107a7e8>] ? sched_clock_local+0x42/0x12e [128095.480138] [<c10a84cf>] lock_acquire+0x7d/0x195 [128095.480138] [<c114971b>] ? page_referenced+0x87/0x5e3 [128095.480138] [<c15b3671>] mutex_lock_nested+0x6c/0x3a7 [128095.480138] [<c114971b>] ? page_referenced+0x87/0x5e3 [128095.480138] [<c114971b>] ? page_referenced+0x87/0x5e3 [128095.480138] [<c11661d5>] ? mem_cgroup_charge_statistics.isra.24+0x61/0x9e [128095.480138] [<c114971b>] page_referenced+0x87/0x5e3 [128095.480138] [<f8433030>] ? raid0_congested+0x26/0x8a [raid0] [128095.480138] [<c112b9c7>] shrink_page_list+0x3d9/0x947 [128095.480138] [<c10a6457>] ? trace_hardirqs_on+0xb/0xd [128095.480138] [<c112c3cf>] shrink_inactive_list+0x155/0x4cb [128095.480138] [<c112cd07>] shrink_lruvec+0x300/0x5ce [128095.480138] [<c112d028>] shrink_zone+0x53/0x14e [128095.480138] [<c112e531>] kswapd+0x517/0xa75 [128095.480138] [<c112e01a>] ? mem_cgroup_shrink_node_zone+0x280/0x280 [128095.480138] [<c10661ff>] kthread+0xa8/0xaa [128095.480138] [<c10a6457>] ? trace_hardirqs_on+0xb/0xd [128095.480138] [<c15bf737>] ret_from_kernel_thread+0x1b/0x28 [128095.480138] [<c1066157>] ? insert_kthread_work+0x63/0x63 which is a false positive caused by hugetlb pmd sharing code which allocates a new pmd from withing mapping->i_mmap_mutex. If this allocation causes reclaim then the lockdep detector complains that we might self-deadlock. This is not correct though, because hugetlb pages are not reclaimable so their mapping will be never touched from the reclaim path. The patch tells lockup detector that hugetlb i_mmap_mutex is special by assigning it a separate lockdep class so it won't report possible deadlocks on unrelated mappings. [peterz@xxxxxxxxxxxxx: comment for annotation] Reported-by: Dave Jones <davej@xxxxxxxxxx> Signed-off-by: Michal Hocko <mhocko@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/hugetlbfs/inode.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff -puN fs/hugetlbfs/inode.c~hugetlb-fix-lockdep-splat-caused-by-pmd-sharing fs/hugetlbfs/inode.c --- a/fs/hugetlbfs/inode.c~hugetlb-fix-lockdep-splat-caused-by-pmd-sharing +++ a/fs/hugetlbfs/inode.c @@ -463,6 +463,14 @@ static struct inode *hugetlbfs_get_root( return inode; } +/* + * Hugetlbfs is not reclaimable; therefore its i_mmap_mutex will never + * be taken from reclaim -- unlike regular filesystems. This needs an + * annotation because huge_pmd_share() does an allocation under + * i_mmap_mutex. + */ +struct lock_class_key hugetlbfs_i_mmap_mutex_key; + static struct inode *hugetlbfs_get_inode(struct super_block *sb, struct inode *dir, umode_t mode, dev_t dev) @@ -474,6 +482,8 @@ static struct inode *hugetlbfs_get_inode struct hugetlbfs_inode_info *info; inode->i_ino = get_next_ino(); inode_init_owner(inode, dir, mode); + lockdep_set_class(&inode->i_mapping->i_mmap_mutex, + &hugetlbfs_i_mmap_mutex_key); inode->i_mapping->a_ops = &hugetlbfs_aops; inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; _ Patches currently in -mm which might be from mhocko@xxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html