From 3d5fe03a3ea013060ebba2a811aeb0f23f56aefa Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Thu, 14 Jan 2016 15:22:26 -0800 Subject: [PATCH] zram/zcomp: use GFP_NOIO to allocate streams We can end up allocating a new compression stream with GFP_KERNEL from within the IO path, which may result is nested (recursive) IO operations. That can introduce problems if the IO path in question is a reclaimer, holding some locks that will deadlock nested IOs. Allocate streams and working memory using GFP_NOIO flag, forbidding recursive IO and FS operations. An example: inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage. git/20158 [HC0[0]:SC0[0]:HE1:SE1] takes: (jbd2_handle){+.+.?.}, at: start_this_handle+0x4ca/0x555 {IN-RECLAIM_FS-W} state was registered at: __lock_acquire+0x8da/0x117b lock_acquire+0x10c/0x1a7 start_this_handle+0x52d/0x555 jbd2__journal_start+0xb4/0x237 __ext4_journal_start_sb+0x108/0x17e ext4_dirty_inode+0x32/0x61 __mark_inode_dirty+0x16b/0x60c iput+0x11e/0x274 __dentry_kill+0x148/0x1b8 shrink_dentry_list+0x274/0x44a prune_dcache_sb+0x4a/0x55 super_cache_scan+0xfc/0x176 shrink_slab.part.14.constprop.25+0x2a2/0x4d3 shrink_zone+0x74/0x140 kswapd+0x6b7/0x930 kthread+0x107/0x10f ret_from_fork+0x3f/0x70 irq event stamp: 138297 hardirqs last enabled at (138297): debug_check_no_locks_freed+0x113/0x12f hardirqs last disabled at (138296): debug_check_no_locks_freed+0x33/0x12f softirqs last enabled at (137818): __do_softirq+0x2d3/0x3e9 softirqs last disabled at (137813): irq_exit+0x41/0x95 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(jbd2_handle); lock(jbd2_handle); *** DEADLOCK *** 5 locks held by git/20158: #0: (sb_writers#7){.+.+.+}, at: [] mnt_want_write+0x24/0x4b #1: (&type->i_mutex_dir_key#2/1){+.+.+.}, at: [] lock_rename+0xd9/0xe3 #2: (&sb->s_type->i_mutex_key#11){+.+.+.}, at: [] lock_two_nondirectories+0x3f/0x6b #3: (&sb->s_type->i_mutex_key#11/4){+.+.+.}, at: [] lock_two_nondirectories+0x66/0x6b #4: (jbd2_handle){+.+.?.}, at: [] start_this_handle+0x4ca/0x555 stack backtrace: CPU: 2 PID: 20158 Comm: git Not tainted 4.1.0-rc7-next-20150615-dbg-00016-g8bdf555-dirty #211 Call Trace: dump_stack+0x4c/0x6e mark_lock+0x384/0x56d mark_held_locks+0x5f/0x76 lockdep_trace_alloc+0xb2/0xb5 kmem_cache_alloc_trace+0x32/0x1e2 zcomp_strm_alloc+0x25/0x73 [zram] zcomp_strm_multi_find+0xe7/0x173 [zram] zcomp_strm_find+0xc/0xe [zram] zram_bvec_rw+0x2ca/0x7e0 [zram] zram_make_request+0x1fa/0x301 [zram] generic_make_request+0x9c/0xdb submit_bio+0xf7/0x120 ext4_io_submit+0x2e/0x43 ext4_bio_write_page+0x1b7/0x300 mpage_submit_page+0x60/0x77 mpage_map_and_submit_buffers+0x10f/0x21d ext4_writepages+0xc8c/0xe1b do_writepages+0x23/0x2c __filemap_fdatawrite_range+0x84/0x8b filemap_flush+0x1c/0x1e ext4_alloc_da_blocks+0xb8/0x117 ext4_rename+0x132/0x6dc ? mark_held_locks+0x5f/0x76 ext4_rename2+0x29/0x2b vfs_rename+0x540/0x636 SyS_renameat2+0x359/0x44d SyS_rename+0x1e/0x20 entry_SYSCALL_64_fastpath+0x12/0x6f [minchan@kernel.org: add stable mark] Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Kyeongdon Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zcomp.c | 4 ++-- drivers/block/zram/zcomp_lz4.c | 2 +- drivers/block/zram/zcomp_lzo.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index 5cb13ca..c536177 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -76,7 +76,7 @@ static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm) */ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp) { - struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL); + struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_NOIO); if (!zstrm) return NULL; @@ -85,7 +85,7 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp) * allocate 2 pages. 1 for compressed data, plus 1 extra for the * case when compressed size is larger than the original one */ - zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1); + zstrm->buffer = (void *)__get_free_pages(GFP_NOIO | __GFP_ZERO, 1); if (!zstrm->private || !zstrm->buffer) { zcomp_strm_free(comp, zstrm); zstrm = NULL; diff --git a/drivers/block/zram/zcomp_lz4.c b/drivers/block/zram/zcomp_lz4.c index f2afb7e..ee44b51 100644 --- a/drivers/block/zram/zcomp_lz4.c +++ b/drivers/block/zram/zcomp_lz4.c @@ -15,7 +15,7 @@ static void *zcomp_lz4_create(void) { - return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL); + return kzalloc(LZ4_MEM_COMPRESS, GFP_NOIO); } static void zcomp_lz4_destroy(void *private) diff --git a/drivers/block/zram/zcomp_lzo.c b/drivers/block/zram/zcomp_lzo.c index da1bc47..683ce04 100644 --- a/drivers/block/zram/zcomp_lzo.c +++ b/drivers/block/zram/zcomp_lzo.c @@ -15,7 +15,7 @@ static void *lzo_create(void) { - return kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); + return kzalloc(LZO1X_MEM_COMPRESS, GFP_NOIO); } static void lzo_destroy(void *private) -- 2.7.4