Commit-ID: 602cae04c4864bb3487dfe4c2126c8d9e7e1614a
Gitweb: https://git.kernel.org/tip/602cae04c4864bb3487dfe4c2126c8d9e7e1614a
Author: Peter Zijlstra <peterz(a)infradead.org>
AuthorDate: Wed, 19 Dec 2018 17:53:50 +0100
Committer: Ingo Molnar <mingo(a)kernel.org>
CommitDate: Mon, 4 Feb 2019 08:44:51 +0100
perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu()
intel_pmu_cpu_prepare() allocated memory for ->shared_regs among other
members of struct cpu_hw_events. This memory is released in
intel_pmu_cpu_dying() which is wrong. The counterpart of the
intel_pmu_cpu_prepare() callback is x86_pmu_dead_cpu().
Otherwise if the CPU fails on the UP path between CPUHP_PERF_X86_PREPARE
and CPUHP_AP_PERF_X86_STARTING then it won't release the memory but
allocate new memory on the next attempt to online the CPU (leaking the
old memory).
Also, if the CPU down path fails between CPUHP_AP_PERF_X86_STARTING and
CPUHP_PERF_X86_PREPARE then the CPU will go back online but never
allocate the memory that was released in x86_pmu_dying_cpu().
Make the memory allocation/free symmetrical in regard to the CPU hotplug
notifier by moving the deallocation to intel_pmu_cpu_dead().
This started in commit:
a7e3ed1e47011 ("perf: Add support for supplementary event registers").
In principle the bug was introduced in v2.6.39 (!), but it will almost
certainly not backport cleanly across the big CPU hotplug rewrite between v4.7-v4.15...
[ bigeasy: Added patch description. ]
[ mingo: Added backporting guidance. ]
Reported-by: He Zhe <zhe.he(a)windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> # With developer hat on
Signed-off-by: Sebastian Andrzej Siewior <bigeasy(a)linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> # With maintainer hat on
Cc: Alexander Shishkin <alexander.shishkin(a)linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com>
Cc: Jiri Olsa <jolsa(a)redhat.com>
Cc: Linus Torvalds <torvalds(a)linux-foundation.org>
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Cc: acme(a)kernel.org
Cc: bp(a)alien8.de
Cc: hpa(a)zytor.com
Cc: jolsa(a)kernel.org
Cc: kan.liang(a)linux.intel.com
Cc: namhyung(a)kernel.org
Cc: <stable(a)vger.kernel.org>
Fixes: a7e3ed1e47011 ("perf: Add support for supplementary event registers").
Link: https://lkml.kernel.org/r/20181219165350.6s3jvyxbibpvlhtq@linutronix.de
Signed-off-by: Ingo Molnar <mingo(a)kernel.org>
---
arch/x86/events/intel/core.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 40e12cfc87f6..daafb893449b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3558,6 +3558,14 @@ static void free_excl_cntrs(int cpu)
}
static void intel_pmu_cpu_dying(int cpu)
+{
+ fini_debug_store_on_cpu(cpu);
+
+ if (x86_pmu.counter_freezing)
+ disable_counter_freeze();
+}
+
+static void intel_pmu_cpu_dead(int cpu)
{
struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
struct intel_shared_regs *pc;
@@ -3570,11 +3578,6 @@ static void intel_pmu_cpu_dying(int cpu)
}
free_excl_cntrs(cpu);
-
- fini_debug_store_on_cpu(cpu);
-
- if (x86_pmu.counter_freezing)
- disable_counter_freeze();
}
static void intel_pmu_sched_task(struct perf_event_context *ctx,
@@ -3663,6 +3666,7 @@ static __initconst const struct x86_pmu core_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
};
static struct attribute *intel_pmu_attrs[];
@@ -3703,6 +3707,8 @@ static __initconst const struct x86_pmu intel_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
+
.guest_get_msrs = intel_guest_get_msrs,
.sched_task = intel_pmu_sched_task,
};
max_register is currently set to 0x1000. This is beyond the mapped
address range of the hardware, so attempts to dump the regmap from
debugfs would trigger a kernel exception.
Furthermore, the useful registers only occupy a small section at the
beginning of the full range. Change the value to 0x9c, the last known
register on the V3s and H3.
On the A31, the register range is extended to support additional
capture channels. Since this is not yet supported, ignore it for now.
Fixes: 5cc7522d8965 ("media: sun6i: Add support for Allwinner CSI V3s")
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Chen-Yu Tsai <wens(a)csie.org>
---
drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
index ee882b66a5ea..332cf81a7ecf 100644
--- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
+++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
@@ -793,7 +793,7 @@ static const struct regmap_config sun6i_csi_regmap_config = {
.reg_bits = 32,
.reg_stride = 4,
.val_bits = 32,
- .max_register = 0x1000,
+ .max_register = 0x9c,
};
static int sun6i_csi_resource_request(struct sun6i_csi_dev *sdev,
--
2.20.1
The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a6279470762c19ba97e454f90798373dccdf6148 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Fri, 25 Jan 2019 11:48:51 +0000
Subject: [PATCH] Btrfs: fix deadlock when allocating tree block during
leaf/node split
When splitting a leaf or node from one of the trees that are modified when
flushing pending block groups (extent, chunk, device and free space trees),
we need to allocate a new tree block, which in turn can result in the need
to allocate a new block group. After allocating the new block group we may
need to flush new block groups that were previously allocated during the
course of the current transaction, which is what may cause a deadlock due
to attempts to write lock twice the same leaf or node, as when splitting
a leaf or node we are holding a write lock on it and its parent node.
The same type of deadlock can also happen when increasing the tree's
height, since we are holding a lock on the existing root while allocating
the tree block to use as the new root node.
An example trace when the deadlock happens during the leaf split path is:
[27175.293054] CPU: 0 PID: 3005 Comm: kworker/u17:6 Tainted: G W 4.19.16 #1
[27175.293942] Hardware name: Penguin Computing Relion 1900/MD90-FS0-ZB-XX, BIOS R15 06/25/2018
[27175.294846] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
(...)
[27175.298384] RSP: 0018:ffffab2087107758 EFLAGS: 00010246
[27175.299269] RAX: 0000000000000bbd RBX: ffff9fadc7141c48 RCX: 0000000000000001
[27175.300155] RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff9fadc7141c48
[27175.301023] RBP: 0000000000000001 R08: ffff9faeb6ac1040 R09: ffff9fa9c0000000
[27175.301887] R10: 0000000000000000 R11: 0000000000000040 R12: ffff9fb21aac8000
[27175.302743] R13: ffff9fb1a64d6a20 R14: 0000000000000001 R15: ffff9fb1a64d6a18
[27175.303601] FS: 0000000000000000(0000) GS:ffff9fb21fa00000(0000) knlGS:0000000000000000
[27175.304468] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[27175.305339] CR2: 00007fdc8743ead8 CR3: 0000000763e0a006 CR4: 00000000003606f0
[27175.306220] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[27175.307087] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[27175.307940] Call Trace:
[27175.308802] btrfs_search_slot+0x779/0x9a0 [btrfs]
[27175.309669] ? update_space_info+0xba/0xe0 [btrfs]
[27175.310534] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.311397] btrfs_insert_item+0x60/0xd0 [btrfs]
[27175.312253] btrfs_create_pending_block_groups+0xee/0x210 [btrfs]
[27175.313116] do_chunk_alloc+0x25f/0x300 [btrfs]
[27175.313984] find_free_extent+0x706/0x10d0 [btrfs]
[27175.314855] btrfs_reserve_extent+0x9b/0x1d0 [btrfs]
[27175.315707] btrfs_alloc_tree_block+0x100/0x5b0 [btrfs]
[27175.316548] split_leaf+0x130/0x610 [btrfs]
[27175.317390] btrfs_search_slot+0x94d/0x9a0 [btrfs]
[27175.318235] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.319087] alloc_reserved_file_extent+0x84/0x2c0 [btrfs]
[27175.319938] __btrfs_run_delayed_refs+0x596/0x1150 [btrfs]
[27175.320792] btrfs_run_delayed_refs+0xed/0x1b0 [btrfs]
[27175.321643] delayed_ref_async_start+0x81/0x90 [btrfs]
[27175.322491] normal_work_helper+0xd0/0x320 [btrfs]
[27175.323328] ? move_linked_works+0x6e/0xa0
[27175.324160] process_one_work+0x191/0x370
[27175.324976] worker_thread+0x4f/0x3b0
[27175.325763] kthread+0xf8/0x130
[27175.326531] ? rescuer_thread+0x320/0x320
[27175.327284] ? kthread_create_worker_on_cpu+0x50/0x50
[27175.328027] ret_from_fork+0x35/0x40
[27175.328741] ---[ end trace 300a1b9f0ac30e26 ]---
Fix this by preventing the flushing of new blocks groups when splitting a
leaf/node and when inserting a new root node for one of the trees modified
by the flushing operation, similar to what is done when COWing a node/leaf
from on of these trees.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202383
Reported-by: Eli V <eliventer(a)gmail.com>
CC: stable(a)vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index f64aad613727..5a6c39b44c84 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -968,6 +968,48 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
return 0;
}
+static struct extent_buffer *alloc_tree_block_no_bg_flush(
+ struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ u64 parent_start,
+ const struct btrfs_disk_key *disk_key,
+ int level,
+ u64 hint,
+ u64 empty_size)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *ret;
+
+ /*
+ * If we are COWing a node/leaf from the extent, chunk, device or free
+ * space trees, make sure that we do not finish block group creation of
+ * pending block groups. We do this to avoid a deadlock.
+ * COWing can result in allocation of a new chunk, and flushing pending
+ * block groups (btrfs_create_pending_block_groups()) can be triggered
+ * when finishing allocation of a new chunk. Creation of a pending block
+ * group modifies the extent, chunk, device and free space trees,
+ * therefore we could deadlock with ourselves since we are holding a
+ * lock on an extent buffer that btrfs_create_pending_block_groups() may
+ * try to COW later.
+ * For similar reasons, we also need to delay flushing pending block
+ * groups when splitting a leaf or node, from one of those trees, since
+ * we are holding a write lock on it and its parent or when inserting a
+ * new root node for one of those trees.
+ */
+ if (root == fs_info->extent_root ||
+ root == fs_info->chunk_root ||
+ root == fs_info->dev_root ||
+ root == fs_info->free_space_root)
+ trans->can_flush_pending_bgs = false;
+
+ ret = btrfs_alloc_tree_block(trans, root, parent_start,
+ root->root_key.objectid, disk_key, level,
+ hint, empty_size);
+ trans->can_flush_pending_bgs = true;
+
+ return ret;
+}
+
/*
* does the dirty work in cow of a single block. The parent block (if
* supplied) is updated to point to the new cow copy. The new buffer is marked
@@ -1015,28 +1057,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
parent_start = parent->start;
- /*
- * If we are COWing a node/leaf from the extent, chunk, device or free
- * space trees, make sure that we do not finish block group creation of
- * pending block groups. We do this to avoid a deadlock.
- * COWing can result in allocation of a new chunk, and flushing pending
- * block groups (btrfs_create_pending_block_groups()) can be triggered
- * when finishing allocation of a new chunk. Creation of a pending block
- * group modifies the extent, chunk, device and free space trees,
- * therefore we could deadlock with ourselves since we are holding a
- * lock on an extent buffer that btrfs_create_pending_block_groups() may
- * try to COW later.
- */
- if (root == fs_info->extent_root ||
- root == fs_info->chunk_root ||
- root == fs_info->dev_root ||
- root == fs_info->free_space_root)
- trans->can_flush_pending_bgs = false;
-
- cow = btrfs_alloc_tree_block(trans, root, parent_start,
- root->root_key.objectid, &disk_key, level,
- search_start, empty_size);
- trans->can_flush_pending_bgs = true;
+ cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
+ level, search_start, empty_size);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -3345,8 +3367,8 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
else
btrfs_node_key(lower, &lower_key, 0);
- c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &lower_key, level, root->node->start, 0);
+ c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
+ root->node->start, 0);
if (IS_ERR(c))
return PTR_ERR(c);
@@ -3475,8 +3497,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
mid = (c_nritems + 1) / 2;
btrfs_node_key(c, &disk_key, mid);
- split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, level, c->start, 0);
+ split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
+ c->start, 0);
if (IS_ERR(split))
return PTR_ERR(split);
@@ -4260,8 +4282,8 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
else
btrfs_item_key(l, &disk_key, mid);
- right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, 0, l->start, 0);
+ right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
+ l->start, 0);
if (IS_ERR(right))
return PTR_ERR(right);
The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a6279470762c19ba97e454f90798373dccdf6148 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Fri, 25 Jan 2019 11:48:51 +0000
Subject: [PATCH] Btrfs: fix deadlock when allocating tree block during
leaf/node split
When splitting a leaf or node from one of the trees that are modified when
flushing pending block groups (extent, chunk, device and free space trees),
we need to allocate a new tree block, which in turn can result in the need
to allocate a new block group. After allocating the new block group we may
need to flush new block groups that were previously allocated during the
course of the current transaction, which is what may cause a deadlock due
to attempts to write lock twice the same leaf or node, as when splitting
a leaf or node we are holding a write lock on it and its parent node.
The same type of deadlock can also happen when increasing the tree's
height, since we are holding a lock on the existing root while allocating
the tree block to use as the new root node.
An example trace when the deadlock happens during the leaf split path is:
[27175.293054] CPU: 0 PID: 3005 Comm: kworker/u17:6 Tainted: G W 4.19.16 #1
[27175.293942] Hardware name: Penguin Computing Relion 1900/MD90-FS0-ZB-XX, BIOS R15 06/25/2018
[27175.294846] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
(...)
[27175.298384] RSP: 0018:ffffab2087107758 EFLAGS: 00010246
[27175.299269] RAX: 0000000000000bbd RBX: ffff9fadc7141c48 RCX: 0000000000000001
[27175.300155] RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff9fadc7141c48
[27175.301023] RBP: 0000000000000001 R08: ffff9faeb6ac1040 R09: ffff9fa9c0000000
[27175.301887] R10: 0000000000000000 R11: 0000000000000040 R12: ffff9fb21aac8000
[27175.302743] R13: ffff9fb1a64d6a20 R14: 0000000000000001 R15: ffff9fb1a64d6a18
[27175.303601] FS: 0000000000000000(0000) GS:ffff9fb21fa00000(0000) knlGS:0000000000000000
[27175.304468] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[27175.305339] CR2: 00007fdc8743ead8 CR3: 0000000763e0a006 CR4: 00000000003606f0
[27175.306220] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[27175.307087] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[27175.307940] Call Trace:
[27175.308802] btrfs_search_slot+0x779/0x9a0 [btrfs]
[27175.309669] ? update_space_info+0xba/0xe0 [btrfs]
[27175.310534] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.311397] btrfs_insert_item+0x60/0xd0 [btrfs]
[27175.312253] btrfs_create_pending_block_groups+0xee/0x210 [btrfs]
[27175.313116] do_chunk_alloc+0x25f/0x300 [btrfs]
[27175.313984] find_free_extent+0x706/0x10d0 [btrfs]
[27175.314855] btrfs_reserve_extent+0x9b/0x1d0 [btrfs]
[27175.315707] btrfs_alloc_tree_block+0x100/0x5b0 [btrfs]
[27175.316548] split_leaf+0x130/0x610 [btrfs]
[27175.317390] btrfs_search_slot+0x94d/0x9a0 [btrfs]
[27175.318235] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.319087] alloc_reserved_file_extent+0x84/0x2c0 [btrfs]
[27175.319938] __btrfs_run_delayed_refs+0x596/0x1150 [btrfs]
[27175.320792] btrfs_run_delayed_refs+0xed/0x1b0 [btrfs]
[27175.321643] delayed_ref_async_start+0x81/0x90 [btrfs]
[27175.322491] normal_work_helper+0xd0/0x320 [btrfs]
[27175.323328] ? move_linked_works+0x6e/0xa0
[27175.324160] process_one_work+0x191/0x370
[27175.324976] worker_thread+0x4f/0x3b0
[27175.325763] kthread+0xf8/0x130
[27175.326531] ? rescuer_thread+0x320/0x320
[27175.327284] ? kthread_create_worker_on_cpu+0x50/0x50
[27175.328027] ret_from_fork+0x35/0x40
[27175.328741] ---[ end trace 300a1b9f0ac30e26 ]---
Fix this by preventing the flushing of new blocks groups when splitting a
leaf/node and when inserting a new root node for one of the trees modified
by the flushing operation, similar to what is done when COWing a node/leaf
from on of these trees.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202383
Reported-by: Eli V <eliventer(a)gmail.com>
CC: stable(a)vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index f64aad613727..5a6c39b44c84 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -968,6 +968,48 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
return 0;
}
+static struct extent_buffer *alloc_tree_block_no_bg_flush(
+ struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ u64 parent_start,
+ const struct btrfs_disk_key *disk_key,
+ int level,
+ u64 hint,
+ u64 empty_size)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *ret;
+
+ /*
+ * If we are COWing a node/leaf from the extent, chunk, device or free
+ * space trees, make sure that we do not finish block group creation of
+ * pending block groups. We do this to avoid a deadlock.
+ * COWing can result in allocation of a new chunk, and flushing pending
+ * block groups (btrfs_create_pending_block_groups()) can be triggered
+ * when finishing allocation of a new chunk. Creation of a pending block
+ * group modifies the extent, chunk, device and free space trees,
+ * therefore we could deadlock with ourselves since we are holding a
+ * lock on an extent buffer that btrfs_create_pending_block_groups() may
+ * try to COW later.
+ * For similar reasons, we also need to delay flushing pending block
+ * groups when splitting a leaf or node, from one of those trees, since
+ * we are holding a write lock on it and its parent or when inserting a
+ * new root node for one of those trees.
+ */
+ if (root == fs_info->extent_root ||
+ root == fs_info->chunk_root ||
+ root == fs_info->dev_root ||
+ root == fs_info->free_space_root)
+ trans->can_flush_pending_bgs = false;
+
+ ret = btrfs_alloc_tree_block(trans, root, parent_start,
+ root->root_key.objectid, disk_key, level,
+ hint, empty_size);
+ trans->can_flush_pending_bgs = true;
+
+ return ret;
+}
+
/*
* does the dirty work in cow of a single block. The parent block (if
* supplied) is updated to point to the new cow copy. The new buffer is marked
@@ -1015,28 +1057,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
parent_start = parent->start;
- /*
- * If we are COWing a node/leaf from the extent, chunk, device or free
- * space trees, make sure that we do not finish block group creation of
- * pending block groups. We do this to avoid a deadlock.
- * COWing can result in allocation of a new chunk, and flushing pending
- * block groups (btrfs_create_pending_block_groups()) can be triggered
- * when finishing allocation of a new chunk. Creation of a pending block
- * group modifies the extent, chunk, device and free space trees,
- * therefore we could deadlock with ourselves since we are holding a
- * lock on an extent buffer that btrfs_create_pending_block_groups() may
- * try to COW later.
- */
- if (root == fs_info->extent_root ||
- root == fs_info->chunk_root ||
- root == fs_info->dev_root ||
- root == fs_info->free_space_root)
- trans->can_flush_pending_bgs = false;
-
- cow = btrfs_alloc_tree_block(trans, root, parent_start,
- root->root_key.objectid, &disk_key, level,
- search_start, empty_size);
- trans->can_flush_pending_bgs = true;
+ cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
+ level, search_start, empty_size);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -3345,8 +3367,8 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
else
btrfs_node_key(lower, &lower_key, 0);
- c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &lower_key, level, root->node->start, 0);
+ c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
+ root->node->start, 0);
if (IS_ERR(c))
return PTR_ERR(c);
@@ -3475,8 +3497,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
mid = (c_nritems + 1) / 2;
btrfs_node_key(c, &disk_key, mid);
- split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, level, c->start, 0);
+ split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
+ c->start, 0);
if (IS_ERR(split))
return PTR_ERR(split);
@@ -4260,8 +4282,8 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
else
btrfs_item_key(l, &disk_key, mid);
- right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, 0, l->start, 0);
+ right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
+ l->start, 0);
if (IS_ERR(right))
return PTR_ERR(right);
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From a6279470762c19ba97e454f90798373dccdf6148 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Fri, 25 Jan 2019 11:48:51 +0000
Subject: [PATCH] Btrfs: fix deadlock when allocating tree block during
leaf/node split
When splitting a leaf or node from one of the trees that are modified when
flushing pending block groups (extent, chunk, device and free space trees),
we need to allocate a new tree block, which in turn can result in the need
to allocate a new block group. After allocating the new block group we may
need to flush new block groups that were previously allocated during the
course of the current transaction, which is what may cause a deadlock due
to attempts to write lock twice the same leaf or node, as when splitting
a leaf or node we are holding a write lock on it and its parent node.
The same type of deadlock can also happen when increasing the tree's
height, since we are holding a lock on the existing root while allocating
the tree block to use as the new root node.
An example trace when the deadlock happens during the leaf split path is:
[27175.293054] CPU: 0 PID: 3005 Comm: kworker/u17:6 Tainted: G W 4.19.16 #1
[27175.293942] Hardware name: Penguin Computing Relion 1900/MD90-FS0-ZB-XX, BIOS R15 06/25/2018
[27175.294846] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
(...)
[27175.298384] RSP: 0018:ffffab2087107758 EFLAGS: 00010246
[27175.299269] RAX: 0000000000000bbd RBX: ffff9fadc7141c48 RCX: 0000000000000001
[27175.300155] RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff9fadc7141c48
[27175.301023] RBP: 0000000000000001 R08: ffff9faeb6ac1040 R09: ffff9fa9c0000000
[27175.301887] R10: 0000000000000000 R11: 0000000000000040 R12: ffff9fb21aac8000
[27175.302743] R13: ffff9fb1a64d6a20 R14: 0000000000000001 R15: ffff9fb1a64d6a18
[27175.303601] FS: 0000000000000000(0000) GS:ffff9fb21fa00000(0000) knlGS:0000000000000000
[27175.304468] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[27175.305339] CR2: 00007fdc8743ead8 CR3: 0000000763e0a006 CR4: 00000000003606f0
[27175.306220] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[27175.307087] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[27175.307940] Call Trace:
[27175.308802] btrfs_search_slot+0x779/0x9a0 [btrfs]
[27175.309669] ? update_space_info+0xba/0xe0 [btrfs]
[27175.310534] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.311397] btrfs_insert_item+0x60/0xd0 [btrfs]
[27175.312253] btrfs_create_pending_block_groups+0xee/0x210 [btrfs]
[27175.313116] do_chunk_alloc+0x25f/0x300 [btrfs]
[27175.313984] find_free_extent+0x706/0x10d0 [btrfs]
[27175.314855] btrfs_reserve_extent+0x9b/0x1d0 [btrfs]
[27175.315707] btrfs_alloc_tree_block+0x100/0x5b0 [btrfs]
[27175.316548] split_leaf+0x130/0x610 [btrfs]
[27175.317390] btrfs_search_slot+0x94d/0x9a0 [btrfs]
[27175.318235] btrfs_insert_empty_items+0x67/0xc0 [btrfs]
[27175.319087] alloc_reserved_file_extent+0x84/0x2c0 [btrfs]
[27175.319938] __btrfs_run_delayed_refs+0x596/0x1150 [btrfs]
[27175.320792] btrfs_run_delayed_refs+0xed/0x1b0 [btrfs]
[27175.321643] delayed_ref_async_start+0x81/0x90 [btrfs]
[27175.322491] normal_work_helper+0xd0/0x320 [btrfs]
[27175.323328] ? move_linked_works+0x6e/0xa0
[27175.324160] process_one_work+0x191/0x370
[27175.324976] worker_thread+0x4f/0x3b0
[27175.325763] kthread+0xf8/0x130
[27175.326531] ? rescuer_thread+0x320/0x320
[27175.327284] ? kthread_create_worker_on_cpu+0x50/0x50
[27175.328027] ret_from_fork+0x35/0x40
[27175.328741] ---[ end trace 300a1b9f0ac30e26 ]---
Fix this by preventing the flushing of new blocks groups when splitting a
leaf/node and when inserting a new root node for one of the trees modified
by the flushing operation, similar to what is done when COWing a node/leaf
from on of these trees.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202383
Reported-by: Eli V <eliventer(a)gmail.com>
CC: stable(a)vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index f64aad613727..5a6c39b44c84 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -968,6 +968,48 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
return 0;
}
+static struct extent_buffer *alloc_tree_block_no_bg_flush(
+ struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ u64 parent_start,
+ const struct btrfs_disk_key *disk_key,
+ int level,
+ u64 hint,
+ u64 empty_size)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct extent_buffer *ret;
+
+ /*
+ * If we are COWing a node/leaf from the extent, chunk, device or free
+ * space trees, make sure that we do not finish block group creation of
+ * pending block groups. We do this to avoid a deadlock.
+ * COWing can result in allocation of a new chunk, and flushing pending
+ * block groups (btrfs_create_pending_block_groups()) can be triggered
+ * when finishing allocation of a new chunk. Creation of a pending block
+ * group modifies the extent, chunk, device and free space trees,
+ * therefore we could deadlock with ourselves since we are holding a
+ * lock on an extent buffer that btrfs_create_pending_block_groups() may
+ * try to COW later.
+ * For similar reasons, we also need to delay flushing pending block
+ * groups when splitting a leaf or node, from one of those trees, since
+ * we are holding a write lock on it and its parent or when inserting a
+ * new root node for one of those trees.
+ */
+ if (root == fs_info->extent_root ||
+ root == fs_info->chunk_root ||
+ root == fs_info->dev_root ||
+ root == fs_info->free_space_root)
+ trans->can_flush_pending_bgs = false;
+
+ ret = btrfs_alloc_tree_block(trans, root, parent_start,
+ root->root_key.objectid, disk_key, level,
+ hint, empty_size);
+ trans->can_flush_pending_bgs = true;
+
+ return ret;
+}
+
/*
* does the dirty work in cow of a single block. The parent block (if
* supplied) is updated to point to the new cow copy. The new buffer is marked
@@ -1015,28 +1057,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
parent_start = parent->start;
- /*
- * If we are COWing a node/leaf from the extent, chunk, device or free
- * space trees, make sure that we do not finish block group creation of
- * pending block groups. We do this to avoid a deadlock.
- * COWing can result in allocation of a new chunk, and flushing pending
- * block groups (btrfs_create_pending_block_groups()) can be triggered
- * when finishing allocation of a new chunk. Creation of a pending block
- * group modifies the extent, chunk, device and free space trees,
- * therefore we could deadlock with ourselves since we are holding a
- * lock on an extent buffer that btrfs_create_pending_block_groups() may
- * try to COW later.
- */
- if (root == fs_info->extent_root ||
- root == fs_info->chunk_root ||
- root == fs_info->dev_root ||
- root == fs_info->free_space_root)
- trans->can_flush_pending_bgs = false;
-
- cow = btrfs_alloc_tree_block(trans, root, parent_start,
- root->root_key.objectid, &disk_key, level,
- search_start, empty_size);
- trans->can_flush_pending_bgs = true;
+ cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
+ level, search_start, empty_size);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -3345,8 +3367,8 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
else
btrfs_node_key(lower, &lower_key, 0);
- c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &lower_key, level, root->node->start, 0);
+ c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
+ root->node->start, 0);
if (IS_ERR(c))
return PTR_ERR(c);
@@ -3475,8 +3497,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
mid = (c_nritems + 1) / 2;
btrfs_node_key(c, &disk_key, mid);
- split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, level, c->start, 0);
+ split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
+ c->start, 0);
if (IS_ERR(split))
return PTR_ERR(split);
@@ -4260,8 +4282,8 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
else
btrfs_item_key(l, &disk_key, mid);
- right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
- &disk_key, 0, l->start, 0);
+ right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
+ l->start, 0);
if (IS_ERR(right))
return PTR_ERR(right);