Fixes for 4.19

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-4.19/btrfs-use-nofs-allocations-for-running-delayed-items.patch b/queue-4.19/btrfs-use-nofs-allocations-for-running-delayed-items.patch
new file mode 100644 (file)
index 0000000..4df0d3a
--- /dev/null
+++ b/queue-4.19/btrfs-use-nofs-allocations-for-running-delayed-items.patch
@@ -0,0 +1,236 @@
+From dc88abdfccbf23fb4a72eece20401173bbc91ee0 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Thu, 19 Mar 2020 10:11:32 -0400
+Subject: btrfs: use nofs allocations for running delayed items
+
+From: Josef Bacik <josef@toxicpanda.com>
+
+[ Upstream commit 351cbf6e4410e7ece05e35d0a07320538f2418b4 ]
+
+Zygo reported the following lockdep splat while testing the balance
+patches
+
+======================================================
+WARNING: possible circular locking dependency detected
+5.6.0-c6f0579d496a+ #53 Not tainted
+------------------------------------------------------
+kswapd0/1133 is trying to acquire lock:
+ffff888092f622c0 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node+0x7c/0x5b0
+
+but task is already holding lock:
+ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30
+
+which lock already depends on the new lock.
+
+the existing dependency chain (in reverse order) is:
+
+-> #1 (fs_reclaim){+.+.}:
+       fs_reclaim_acquire.part.91+0x29/0x30
+       fs_reclaim_acquire+0x19/0x20
+       kmem_cache_alloc_trace+0x32/0x740
+       add_block_entry+0x45/0x260
+       btrfs_ref_tree_mod+0x6e2/0x8b0
+       btrfs_alloc_tree_block+0x789/0x880
+       alloc_tree_block_no_bg_flush+0xc6/0xf0
+       __btrfs_cow_block+0x270/0x940
+       btrfs_cow_block+0x1ba/0x3a0
+       btrfs_search_slot+0x999/0x1030
+       btrfs_insert_empty_items+0x81/0xe0
+       btrfs_insert_delayed_items+0x128/0x7d0
+       __btrfs_run_delayed_items+0xf4/0x2a0
+       btrfs_run_delayed_items+0x13/0x20
+       btrfs_commit_transaction+0x5cc/0x1390
+       insert_balance_item.isra.39+0x6b2/0x6e0
+       btrfs_balance+0x72d/0x18d0
+       btrfs_ioctl_balance+0x3de/0x4c0
+       btrfs_ioctl+0x30ab/0x44a0
+       ksys_ioctl+0xa1/0xe0
+       __x64_sys_ioctl+0x43/0x50
+       do_syscall_64+0x77/0x2c0
+       entry_SYSCALL_64_after_hwframe+0x49/0xbe
+
+-> #0 (&delayed_node->mutex){+.+.}:
+       __lock_acquire+0x197e/0x2550
+       lock_acquire+0x103/0x220
+       __mutex_lock+0x13d/0xce0
+       mutex_lock_nested+0x1b/0x20
+       __btrfs_release_delayed_node+0x7c/0x5b0
+       btrfs_remove_delayed_node+0x49/0x50
+       btrfs_evict_inode+0x6fc/0x900
+       evict+0x19a/0x2c0
+       dispose_list+0xa0/0xe0
+       prune_icache_sb+0xbd/0xf0
+       super_cache_scan+0x1b5/0x250
+       do_shrink_slab+0x1f6/0x530
+       shrink_slab+0x32e/0x410
+       shrink_node+0x2a5/0xba0
+       balance_pgdat+0x4bd/0x8a0
+       kswapd+0x35a/0x800
+       kthread+0x1e9/0x210
+       ret_from_fork+0x3a/0x50
+
+other info that might help us debug this:
+
+ Possible unsafe locking scenario:
+
+       CPU0                    CPU1
+       ----                    ----
+  lock(fs_reclaim);
+                               lock(&delayed_node->mutex);
+                               lock(fs_reclaim);
+  lock(&delayed_node->mutex);
+
+ *** DEADLOCK ***
+
+3 locks held by kswapd0/1133:
+ #0: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30
+ #1: ffffffff8fc380d8 (shrinker_rwsem){++++}, at: shrink_slab+0x1e8/0x410
+ #2: ffff8881e0e6c0e8 (&type->s_umount_key#42){++++}, at: trylock_super+0x1b/0x70
+
+stack backtrace:
+CPU: 2 PID: 1133 Comm: kswapd0 Not tainted 5.6.0-c6f0579d496a+ #53
+Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
+Call Trace:
+ dump_stack+0xc1/0x11a
+ print_circular_bug.isra.38.cold.57+0x145/0x14a
+ check_noncircular+0x2a9/0x2f0
+ ? print_circular_bug.isra.38+0x130/0x130
+ ? stack_trace_consume_entry+0x90/0x90
+ ? save_trace+0x3cc/0x420
+ __lock_acquire+0x197e/0x2550
+ ? btrfs_inode_clear_file_extent_range+0x9b/0xb0
+ ? register_lock_class+0x960/0x960
+ lock_acquire+0x103/0x220
+ ? __btrfs_release_delayed_node+0x7c/0x5b0
+ __mutex_lock+0x13d/0xce0
+ ? __btrfs_release_delayed_node+0x7c/0x5b0
+ ? __asan_loadN+0xf/0x20
+ ? pvclock_clocksource_read+0xeb/0x190
+ ? __btrfs_release_delayed_node+0x7c/0x5b0
+ ? mutex_lock_io_nested+0xc20/0xc20
+ ? __kasan_check_read+0x11/0x20
+ ? check_chain_key+0x1e6/0x2e0
+ mutex_lock_nested+0x1b/0x20
+ ? mutex_lock_nested+0x1b/0x20
+ __btrfs_release_delayed_node+0x7c/0x5b0
+ btrfs_remove_delayed_node+0x49/0x50
+ btrfs_evict_inode+0x6fc/0x900
+ ? btrfs_setattr+0x840/0x840
+ ? do_raw_spin_unlock+0xa8/0x140
+ evict+0x19a/0x2c0
+ dispose_list+0xa0/0xe0
+ prune_icache_sb+0xbd/0xf0
+ ? invalidate_inodes+0x310/0x310
+ super_cache_scan+0x1b5/0x250
+ do_shrink_slab+0x1f6/0x530
+ shrink_slab+0x32e/0x410
+ ? do_shrink_slab+0x530/0x530
+ ? do_shrink_slab+0x530/0x530
+ ? __kasan_check_read+0x11/0x20
+ ? mem_cgroup_protected+0x13d/0x260
+ shrink_node+0x2a5/0xba0
+ balance_pgdat+0x4bd/0x8a0
+ ? mem_cgroup_shrink_node+0x490/0x490
+ ? _raw_spin_unlock_irq+0x27/0x40
+ ? finish_task_switch+0xce/0x390
+ ? rcu_read_lock_bh_held+0xb0/0xb0
+ kswapd+0x35a/0x800
+ ? _raw_spin_unlock_irqrestore+0x4c/0x60
+ ? balance_pgdat+0x8a0/0x8a0
+ ? finish_wait+0x110/0x110
+ ? __kasan_check_read+0x11/0x20
+ ? __kthread_parkme+0xc6/0xe0
+ ? balance_pgdat+0x8a0/0x8a0
+ kthread+0x1e9/0x210
+ ? kthread_create_worker_on_cpu+0xc0/0xc0
+ ret_from_fork+0x3a/0x50
+
+This is because we hold that delayed node's mutex while doing tree
+operations.  Fix this by just wrapping the searches in nofs.
+
+CC: stable@vger.kernel.org # 4.4+
+Signed-off-by: Josef Bacik <josef@toxicpanda.com>
+Reviewed-by: David Sterba <dsterba@suse.com>
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ fs/btrfs/delayed-inode.c | 13 +++++++++++++
+ 1 file changed, 13 insertions(+)
+
+diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
+index e9522f2f25ccb..7374fb23381ca 100644
+--- a/fs/btrfs/delayed-inode.c
++++ b/fs/btrfs/delayed-inode.c
+@@ -6,6 +6,7 @@
+ 
+ #include <linux/slab.h>
+ #include <linux/iversion.h>
++#include <linux/sched/mm.h>
+ #include "delayed-inode.h"
+ #include "disk-io.h"
+ #include "transaction.h"
+@@ -801,11 +802,14 @@ static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans,
+                                    struct btrfs_delayed_item *delayed_item)
+ {
+       struct extent_buffer *leaf;
++      unsigned int nofs_flag;
+       char *ptr;
+       int ret;
+ 
++      nofs_flag = memalloc_nofs_save();
+       ret = btrfs_insert_empty_item(trans, root, path, &delayed_item->key,
+                                     delayed_item->data_len);
++      memalloc_nofs_restore(nofs_flag);
+       if (ret < 0 && ret != -EEXIST)
+               return ret;
+ 
+@@ -933,6 +937,7 @@ static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans,
+                                     struct btrfs_delayed_node *node)
+ {
+       struct btrfs_delayed_item *curr, *prev;
++      unsigned int nofs_flag;
+       int ret = 0;
+ 
+ do_again:
+@@ -941,7 +946,9 @@ static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans,
+       if (!curr)
+               goto delete_fail;
+ 
++      nofs_flag = memalloc_nofs_save();
+       ret = btrfs_search_slot(trans, root, &curr->key, path, -1, 1);
++      memalloc_nofs_restore(nofs_flag);
+       if (ret < 0)
+               goto delete_fail;
+       else if (ret > 0) {
+@@ -1008,6 +1015,7 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
+       struct btrfs_key key;
+       struct btrfs_inode_item *inode_item;
+       struct extent_buffer *leaf;
++      unsigned int nofs_flag;
+       int mod;
+       int ret;
+ 
+@@ -1020,7 +1028,9 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
+       else
+               mod = 1;
+ 
++      nofs_flag = memalloc_nofs_save();
+       ret = btrfs_lookup_inode(trans, root, path, &key, mod);
++      memalloc_nofs_restore(nofs_flag);
+       if (ret > 0) {
+               btrfs_release_path(path);
+               return -ENOENT;
+@@ -1071,7 +1081,10 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
+ 
+       key.type = BTRFS_INODE_EXTREF_KEY;
+       key.offset = -1;
++
++      nofs_flag = memalloc_nofs_save();
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
++      memalloc_nofs_restore(nofs_flag);
+       if (ret < 0)
+               goto err_out;
+       ASSERT(ret);
+-- 
+2.20.1
+

diff --git a/queue-4.19/series b/queue-4.19/series
index 6bdcc169223d4454fc1c11807cc94dbb9d5b96f5..cb243b766827cb03ad2d32a25c38e2999b6d577a 100644 (file)
--- a/queue-4.19/series
+++ b/queue-4.19/series
@@ -129,3 +129,4 @@ powerpc-kprobes-ignore-traps-that-happened-in-real-mode.patch
 scsi-mpt3sas-fix-kernel-panic-observed-on-soft-hba-unplug.patch
 powerpc-add-attributes-for-setjmp-longjmp.patch
 powerpc-make-setjmp-longjmp-signature-standard.patch
+btrfs-use-nofs-allocations-for-running-delayed-items.patch