The patch titled
Subject: radix tree: fix multi-order iteration race
has been removed from the -mm tree. Its filename was
radix-tree-fix-multi-order-iteration-race.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Ross Zwisler <ross.zwisler(a)linux.intel.com>
Subject: radix tree: fix multi-order iteration race
Fix a race in the multi-order iteration code which causes the kernel to
hit a GP fault. This was first seen with a production v4.15 based kernel
(4.15.6-300.fc27.x86_64) utilizing a DAX workload which used order 9 PMD
DAX entries.
The race has to do with how we tear down multi-order sibling entries when
we are removing an item from the tree. Remember for example that an order
2 entry looks like this:
struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]
where 'entry' is in some slot in the struct radix_tree_node, and the three
slots following 'entry' contain sibling pointers which point back to
'entry.'
When we delete 'entry' from the tree, we call :
radix_tree_delete()
radix_tree_delete_item()
__radix_tree_delete()
replace_slot()
replace_slot() first removes the siblings in order from the first to the
last, then at then replaces 'entry' with NULL. This means that for a
brief period of time we end up with one or more of the siblings removed,
so:
struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]
This causes an issue if you have a reader iterating over the slots in the
tree via radix_tree_for_each_slot() while only under
rcu_read_lock()/rcu_read_unlock() protection. This is a common case in
mm/filemap.c.
The issue is that when __radix_tree_next_slot() => skip_siblings() tries
to skip over the sibling entries in the slots, it currently does so with
an exact match on the slot directly preceding our current slot. Normally
this works:
V preceding slot
struct radix_tree_node.slots[] = [entry][sibling][sibling][sibling]
^ current slot
This lets you find the first sibling, and you skip them all in order.
But in the case where one of the siblings is NULL, that slot is skipped
and then our sibling detection is interrupted:
V preceding slot
struct radix_tree_node.slots[] = [entry][NULL][sibling][sibling]
^ current slot
This means that the sibling pointers aren't recognized since they point
all the way back to 'entry', so we think that they are normal internal
radix tree pointers. This causes us to think we need to walk down to a
struct radix_tree_node starting at the address of 'entry'.
In a real running kernel this will crash the thread with a GP fault when
you try and dereference the slots in your broken node starting at 'entry'.
We fix this race by fixing the way that skip_siblings() detects sibling
nodes. Instead of testing against the preceding slot we instead look for
siblings via is_sibling_entry() which compares against the position of the
struct radix_tree_node.slots[] array. This ensures that sibling entries
are properly identified, even if they are no longer contiguous with the
'entry' they point to.
Link: http://lkml.kernel.org/r/20180503192430.7582-6-ross.zwisler@linux.intel.com
Fixes: 148deab223b2 ("radix-tree: improve multiorder iterators")
Signed-off-by: Ross Zwisler <ross.zwisler(a)linux.intel.com>
Reported-by: CR, Sapthagirish <sapthagirish.cr(a)intel.com>
Reviewed-by: Jan Kara <jack(a)suse.cz>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: Dan Williams <dan.j.williams(a)intel.com>
Cc: Dave Chinner <david(a)fromorbit.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
lib/radix-tree.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff -puN lib/radix-tree.c~radix-tree-fix-multi-order-iteration-race lib/radix-tree.c
--- a/lib/radix-tree.c~radix-tree-fix-multi-order-iteration-race
+++ a/lib/radix-tree.c
@@ -1612,11 +1612,9 @@ static void set_iter_tags(struct radix_t
static void __rcu **skip_siblings(struct radix_tree_node **nodep,
void __rcu **slot, struct radix_tree_iter *iter)
{
- void *sib = node_to_entry(slot - 1);
-
while (iter->index < iter->next_index) {
*nodep = rcu_dereference_raw(*slot);
- if (*nodep && *nodep != sib)
+ if (*nodep && !is_sibling_entry(iter->node, *nodep))
return slot;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
@@ -1631,7 +1629,7 @@ void __rcu **__radix_tree_next_slot(void
struct radix_tree_iter *iter, unsigned flags)
{
unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
- struct radix_tree_node *node = rcu_dereference_raw(*slot);
+ struct radix_tree_node *node;
slot = skip_siblings(&node, slot, iter);
_
Patches currently in -mm which might be from ross.zwisler(a)linux.intel.com are
Hello Greg,
Here are trivial backports for upstream commit, which is tagged as stable:
02a3307aa9c2 ("btrfs: fix reading stale metadata blocks after degraded
raid1 mounts")
Regards,
Nikolay
From: Sudip Mukherjee <sudipm.mukherjee(a)gmail.com>
While whitelisting Micron M500DC drives, the tweaked blacklist entry
enabled queued TRIM from M500IT variants also. But these do not support
queued TRIM. And while using those SSDs with the latest kernel we have
seen errors and even the partition table getting corrupted.
Some part from the dmesg:
[ 6.727384] ata1.00: ATA-9: Micron_M500IT_MTFDDAK060MBD, MU01, max UDMA/133
[ 6.727390] ata1.00: 117231408 sectors, multi 16: LBA48 NCQ (depth 31/32), AA
[ 6.741026] ata1.00: supports DRM functions and may not be fully accessible
[ 6.759887] ata1.00: configured for UDMA/133
[ 6.762256] scsi 0:0:0:0: Direct-Access ATA Micron_M500IT_MT MU01 PQ: 0 ANSI: 5
and then for the error:
[ 120.860334] ata1.00: exception Emask 0x1 SAct 0x7ffc0007 SErr 0x0 action 0x6 frozen
[ 120.860338] ata1.00: irq_stat 0x40000008
[ 120.860342] ata1.00: failed command: SEND FPDMA QUEUED
[ 120.860351] ata1.00: cmd 64/01:00:00:00:00/00:00:00:00:00/a0 tag 0 ncq dma 512 out
res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x5 (timeout)
[ 120.860353] ata1.00: status: { DRDY }
[ 120.860543] ata1: hard resetting link
[ 121.166128] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[ 121.166376] ata1.00: supports DRM functions and may not be fully accessible
[ 121.186238] ata1.00: supports DRM functions and may not be fully accessible
[ 121.204445] ata1.00: configured for UDMA/133
[ 121.204454] ata1.00: device reported invalid CHS sector 0
[ 121.204541] sd 0:0:0:0: [sda] tag#18 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x08
[ 121.204546] sd 0:0:0:0: [sda] tag#18 Sense Key : 0x5 [current]
[ 121.204550] sd 0:0:0:0: [sda] tag#18 ASC=0x21 ASCQ=0x4
[ 121.204555] sd 0:0:0:0: [sda] tag#18 CDB: opcode=0x93 93 08 00 00 00 00 00 04 28 80 00 00 00 30 00 00
[ 121.204559] print_req_error: I/O error, dev sda, sector 272512
After few reboots with these errors, and the SSD is corrupted.
After blacklisting it, the errors are not seen and the SSD does not get
corrupted any more.
Fixes: 243918be6393 ("libata: Do not blacklist Micron M500DC")
Cc: Martin K. Petersen <martin.petersen(a)oracle.com>
Cc: stable(a)vger.kernel.org
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee(a)gmail.com>
---
This is a resend of v1.
v2 was blacklisting all Micron SSDs but Martin has confirmed that
only M500IT with MU01 firmware is affected.
drivers/ata/libata-core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index eaf0f42f6f28..cdcd55cb2a9a 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4554,6 +4554,8 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
{ "SanDisk SD7UB3Q*G1001", NULL, ATA_HORKAGE_NOLPM, },
/* devices that don't properly handle queued TRIM commands */
+ { "Micron_M500IT_*", "MU01", ATA_HORKAGE_NO_NCQ_TRIM |
+ ATA_HORKAGE_ZERO_AFTER_TRIM, },
{ "Micron_M500_*", NULL, ATA_HORKAGE_NO_NCQ_TRIM |
ATA_HORKAGE_ZERO_AFTER_TRIM, },
{ "Crucial_CT*M500*", NULL, ATA_HORKAGE_NO_NCQ_TRIM |
--
2.11.0
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 fe816d0f1d4c31c4c31d42ca78a87660565fc800 Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <nborisov(a)suse.com>
Date: Fri, 27 Apr 2018 12:21:53 +0300
Subject: [PATCH] btrfs: Fix delalloc inodes invalidation during transaction
abort
When a transaction is aborted btrfs_cleanup_transaction is called to
cleanup all the various in-flight bits and pieces which migth be
active. One of those is delalloc inodes - inodes which have dirty
pages which haven't been persisted yet. Currently the process of
freeing such delalloc inodes in exceptional circumstances such as
transaction abort boiled down to calling btrfs_invalidate_inodes whose
sole job is to invalidate the dentries for all inodes related to a
root. This is in fact wrong and insufficient since such delalloc inodes
will likely have pending pages or ordered-extents and will be linked to
the sb->s_inode_list. This means that unmounting a btrfs instance with
an aborted transaction could potentially lead inodes/their pages
visible to the system long after their superblock has been freed. This
in turn leads to a "use-after-free" situation once page shrink is
triggered. This situation could be simulated by running generic/019
which would cause such inodes to be left hanging, followed by
generic/176 which causes memory pressure and page eviction which lead
to touching the freed super block instance. This situation is
additionally detected by the unmount code of VFS with the following
message:
"VFS: Busy inodes after unmount of Self-destruct in 5 seconds. Have a nice day..."
Additionally btrfs hits WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
in free_fs_root for the same reason.
This patch aims to rectify the sitaution by doing the following:
1. Change btrfs_destroy_delalloc_inodes so that it calls
invalidate_inode_pages2 for every inode on the delalloc list, this
ensures that all the pages of the inode are released. This function
boils down to calling btrfs_releasepage. During test I observed cases
where inodes on the delalloc list were having an i_count of 0, so this
necessitates using igrab to be sure we are working on a non-freed inode.
2. Since calling btrfs_releasepage might queue delayed iputs move the
call out to btrfs_cleanup_transaction in btrfs_error_commit_super before
calling run_delayed_iputs for the last time. This is necessary to ensure
that delayed iputs are run.
Note: this patch is tagged for 4.14 stable but the fix applies to older
versions too but needs to be backported manually due to conflicts.
CC: stable(a)vger.kernel.org # 4.14.x: 2b8773313494: btrfs: Split btrfs_del_delalloc_inode into 2 functions
CC: stable(a)vger.kernel.org # 4.14.x
Signed-off-by: Nikolay Borisov <nborisov(a)suse.com>
Reviewed-by: David Sterba <dsterba(a)suse.com>
[ add comment to igrab ]
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60caa68c3618..c3504b4d281b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3818,6 +3818,7 @@ void close_ctree(struct btrfs_fs_info *fs_info)
set_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags);
btrfs_free_qgroup_config(fs_info);
+ ASSERT(list_empty(&fs_info->delalloc_roots));
if (percpu_counter_sum(&fs_info->delalloc_bytes)) {
btrfs_info(fs_info, "at unmount delalloc count %lld",
@@ -4125,15 +4126,15 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info)
static void btrfs_error_commit_super(struct btrfs_fs_info *fs_info)
{
+ /* cleanup FS via transaction */
+ btrfs_cleanup_transaction(fs_info);
+
mutex_lock(&fs_info->cleaner_mutex);
btrfs_run_delayed_iputs(fs_info);
mutex_unlock(&fs_info->cleaner_mutex);
down_write(&fs_info->cleanup_work_sem);
up_write(&fs_info->cleanup_work_sem);
-
- /* cleanup FS via transaction */
- btrfs_cleanup_transaction(fs_info);
}
static void btrfs_destroy_ordered_extents(struct btrfs_root *root)
@@ -4258,19 +4259,23 @@ static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)
list_splice_init(&root->delalloc_inodes, &splice);
while (!list_empty(&splice)) {
+ struct inode *inode = NULL;
btrfs_inode = list_first_entry(&splice, struct btrfs_inode,
delalloc_inodes);
-
- list_del_init(&btrfs_inode->delalloc_inodes);
- clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
- &btrfs_inode->runtime_flags);
+ __btrfs_del_delalloc_inode(root, btrfs_inode);
spin_unlock(&root->delalloc_lock);
- btrfs_invalidate_inodes(btrfs_inode->root);
-
+ /*
+ * Make sure we get a live inode and that it'll not disappear
+ * meanwhile.
+ */
+ inode = igrab(&btrfs_inode->vfs_inode);
+ if (inode) {
+ invalidate_inode_pages2(inode->i_mapping);
+ iput(inode);
+ }
spin_lock(&root->delalloc_lock);
}
-
spin_unlock(&root->delalloc_lock);
}
@@ -4286,7 +4291,6 @@ static void btrfs_destroy_all_delalloc_inodes(struct btrfs_fs_info *fs_info)
while (!list_empty(&splice)) {
root = list_first_entry(&splice, struct btrfs_root,
delalloc_root);
- list_del_init(&root->delalloc_root);
root = btrfs_grab_fs_root(root);
BUG_ON(!root);
spin_unlock(&fs_info->delalloc_root_lock);
The patch below does not apply to the 4.16-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 fe816d0f1d4c31c4c31d42ca78a87660565fc800 Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <nborisov(a)suse.com>
Date: Fri, 27 Apr 2018 12:21:53 +0300
Subject: [PATCH] btrfs: Fix delalloc inodes invalidation during transaction
abort
When a transaction is aborted btrfs_cleanup_transaction is called to
cleanup all the various in-flight bits and pieces which migth be
active. One of those is delalloc inodes - inodes which have dirty
pages which haven't been persisted yet. Currently the process of
freeing such delalloc inodes in exceptional circumstances such as
transaction abort boiled down to calling btrfs_invalidate_inodes whose
sole job is to invalidate the dentries for all inodes related to a
root. This is in fact wrong and insufficient since such delalloc inodes
will likely have pending pages or ordered-extents and will be linked to
the sb->s_inode_list. This means that unmounting a btrfs instance with
an aborted transaction could potentially lead inodes/their pages
visible to the system long after their superblock has been freed. This
in turn leads to a "use-after-free" situation once page shrink is
triggered. This situation could be simulated by running generic/019
which would cause such inodes to be left hanging, followed by
generic/176 which causes memory pressure and page eviction which lead
to touching the freed super block instance. This situation is
additionally detected by the unmount code of VFS with the following
message:
"VFS: Busy inodes after unmount of Self-destruct in 5 seconds. Have a nice day..."
Additionally btrfs hits WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
in free_fs_root for the same reason.
This patch aims to rectify the sitaution by doing the following:
1. Change btrfs_destroy_delalloc_inodes so that it calls
invalidate_inode_pages2 for every inode on the delalloc list, this
ensures that all the pages of the inode are released. This function
boils down to calling btrfs_releasepage. During test I observed cases
where inodes on the delalloc list were having an i_count of 0, so this
necessitates using igrab to be sure we are working on a non-freed inode.
2. Since calling btrfs_releasepage might queue delayed iputs move the
call out to btrfs_cleanup_transaction in btrfs_error_commit_super before
calling run_delayed_iputs for the last time. This is necessary to ensure
that delayed iputs are run.
Note: this patch is tagged for 4.14 stable but the fix applies to older
versions too but needs to be backported manually due to conflicts.
CC: stable(a)vger.kernel.org # 4.14.x: 2b8773313494: btrfs: Split btrfs_del_delalloc_inode into 2 functions
CC: stable(a)vger.kernel.org # 4.14.x
Signed-off-by: Nikolay Borisov <nborisov(a)suse.com>
Reviewed-by: David Sterba <dsterba(a)suse.com>
[ add comment to igrab ]
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60caa68c3618..c3504b4d281b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3818,6 +3818,7 @@ void close_ctree(struct btrfs_fs_info *fs_info)
set_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags);
btrfs_free_qgroup_config(fs_info);
+ ASSERT(list_empty(&fs_info->delalloc_roots));
if (percpu_counter_sum(&fs_info->delalloc_bytes)) {
btrfs_info(fs_info, "at unmount delalloc count %lld",
@@ -4125,15 +4126,15 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info)
static void btrfs_error_commit_super(struct btrfs_fs_info *fs_info)
{
+ /* cleanup FS via transaction */
+ btrfs_cleanup_transaction(fs_info);
+
mutex_lock(&fs_info->cleaner_mutex);
btrfs_run_delayed_iputs(fs_info);
mutex_unlock(&fs_info->cleaner_mutex);
down_write(&fs_info->cleanup_work_sem);
up_write(&fs_info->cleanup_work_sem);
-
- /* cleanup FS via transaction */
- btrfs_cleanup_transaction(fs_info);
}
static void btrfs_destroy_ordered_extents(struct btrfs_root *root)
@@ -4258,19 +4259,23 @@ static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)
list_splice_init(&root->delalloc_inodes, &splice);
while (!list_empty(&splice)) {
+ struct inode *inode = NULL;
btrfs_inode = list_first_entry(&splice, struct btrfs_inode,
delalloc_inodes);
-
- list_del_init(&btrfs_inode->delalloc_inodes);
- clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
- &btrfs_inode->runtime_flags);
+ __btrfs_del_delalloc_inode(root, btrfs_inode);
spin_unlock(&root->delalloc_lock);
- btrfs_invalidate_inodes(btrfs_inode->root);
-
+ /*
+ * Make sure we get a live inode and that it'll not disappear
+ * meanwhile.
+ */
+ inode = igrab(&btrfs_inode->vfs_inode);
+ if (inode) {
+ invalidate_inode_pages2(inode->i_mapping);
+ iput(inode);
+ }
spin_lock(&root->delalloc_lock);
}
-
spin_unlock(&root->delalloc_lock);
}
@@ -4286,7 +4291,6 @@ static void btrfs_destroy_all_delalloc_inodes(struct btrfs_fs_info *fs_info)
while (!list_empty(&splice)) {
root = list_first_entry(&splice, struct btrfs_root,
delalloc_root);
- list_del_init(&root->delalloc_root);
root = btrfs_grab_fs_root(root);
BUG_ON(!root);
spin_unlock(&fs_info->delalloc_root_lock);
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 6f2f0b394b54e2b159ef969a0b5274e9bbf82ff2 Mon Sep 17 00:00:00 2001
From: Robbie Ko <robbieko(a)synology.com>
Date: Mon, 14 May 2018 10:51:34 +0800
Subject: [PATCH] Btrfs: send, fix invalid access to commit roots due to
concurrent snapshotting
[BUG]
btrfs incremental send BUG happens when creating a snapshot of snapshot
that is being used by send.
[REASON]
The problem can happen if while we are doing a send one of the snapshots
used (parent or send) is snapshotted, because snapshoting implies COWing
the root of the source subvolume/snapshot.
1. When doing an incremental send, the send process will get the commit
roots from the parent and send snapshots, and add references to them
through extent_buffer_get().
2. When a snapshot/subvolume is snapshotted, its root node is COWed
(transaction.c:create_pending_snapshot()).
3. COWing releases the space used by the node immediately, through:
__btrfs_cow_block()
--btrfs_free_tree_block()
----btrfs_add_free_space(bytenr of node)
4. Because send doesn't hold a transaction open, it's possible that
the transaction used to create the snapshot commits, switches the
commit root and the old space used by the previous root node gets
assigned to some other node allocation. Allocation of a new node will
use the existing extent buffer found in memory, which we previously
got a reference through extent_buffer_get(), and allow the extent
buffer's content (pages) to be modified:
btrfs_alloc_tree_block
--btrfs_reserve_extent
----find_free_extent (get bytenr of old node)
--btrfs_init_new_buffer (use bytenr of old node)
----btrfs_find_create_tree_block
------alloc_extent_buffer
--------find_extent_buffer (get old node)
5. So send can access invalid memory content and have unpredictable
behaviour.
[FIX]
So we fix the problem by copying the commit roots of the send and
parent snapshots and use those copies.
CallTrace looks like this:
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.c:1861!
invalid opcode: 0000 [#1] SMP
CPU: 6 PID: 24235 Comm: btrfs Tainted: P O 3.10.105 #23721
ffff88046652d680 ti: ffff88041b720000 task.ti: ffff88041b720000
RIP: 0010:[<ffffffffa08dd0e8>] read_node_slot+0x108/0x110 [btrfs]
RSP: 0018:ffff88041b723b68 EFLAGS: 00010246
RAX: ffff88043ca6b000 RBX: ffff88041b723c50 RCX: ffff880000000000
RDX: 000000000000004c RSI: ffff880314b133f8 RDI: ffff880458b24000
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff88041b723c66
R10: 0000000000000001 R11: 0000000000001000 R12: ffff8803f3e48890
R13: ffff8803f3e48880 R14: ffff880466351800 R15: 0000000000000001
FS: 00007f8c321dc8c0(0000) GS:ffff88047fcc0000(0000)
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
R2: 00007efd1006d000 CR3: 0000000213a24000 CR4: 00000000003407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff88041b723c50 ffff8803f3e48880 ffff8803f3e48890 ffff8803f3e48880
ffff880466351800 0000000000000001 ffffffffa08dd9d7 ffff88041b723c50
ffff8803f3e48880 ffff88041b723c66 ffffffffa08dde85 a9ff88042d2c4400
Call Trace:
[<ffffffffa08dd9d7>] ? tree_move_down.isra.33+0x27/0x50 [btrfs]
[<ffffffffa08dde85>] ? tree_advance+0xb5/0xc0 [btrfs]
[<ffffffffa08e83d4>] ? btrfs_compare_trees+0x2d4/0x760 [btrfs]
[<ffffffffa0982050>] ? finish_inode_if_needed+0x870/0x870 [btrfs]
[<ffffffffa09841ea>] ? btrfs_ioctl_send+0xeda/0x1050 [btrfs]
[<ffffffffa094bd3d>] ? btrfs_ioctl+0x1e3d/0x33f0 [btrfs]
[<ffffffff81111133>] ? handle_pte_fault+0x373/0x990
[<ffffffff8153a096>] ? atomic_notifier_call_chain+0x16/0x20
[<ffffffff81063256>] ? set_task_cpu+0xb6/0x1d0
[<ffffffff811122c3>] ? handle_mm_fault+0x143/0x2a0
[<ffffffff81539cc0>] ? __do_page_fault+0x1d0/0x500
[<ffffffff81062f07>] ? check_preempt_curr+0x57/0x90
[<ffffffff8115075a>] ? do_vfs_ioctl+0x4aa/0x990
[<ffffffff81034f83>] ? do_fork+0x113/0x3b0
[<ffffffff812dd7d7>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[<ffffffff81150cc8>] ? SyS_ioctl+0x88/0xa0
[<ffffffff8153e422>] ? system_call_fastpath+0x16/0x1b
---[ end trace 29576629ee80b2e1 ]---
Fixes: 7069830a9e38 ("Btrfs: add btrfs_compare_trees function")
CC: stable(a)vger.kernel.org # 3.6+
Signed-off-by: Robbie Ko <robbieko(a)synology.com>
Reviewed-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 3fd44835b386..63488f0b850f 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5414,12 +5414,24 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
down_read(&fs_info->commit_root_sem);
left_level = btrfs_header_level(left_root->commit_root);
left_root_level = left_level;
- left_path->nodes[left_level] = left_root->commit_root;
+ left_path->nodes[left_level] =
+ btrfs_clone_extent_buffer(left_root->commit_root);
+ if (!left_path->nodes[left_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(left_path->nodes[left_level]);
right_level = btrfs_header_level(right_root->commit_root);
right_root_level = right_level;
- right_path->nodes[right_level] = right_root->commit_root;
+ right_path->nodes[right_level] =
+ btrfs_clone_extent_buffer(right_root->commit_root);
+ if (!right_path->nodes[right_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(right_path->nodes[right_level]);
up_read(&fs_info->commit_root_sem);
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 6f2f0b394b54e2b159ef969a0b5274e9bbf82ff2 Mon Sep 17 00:00:00 2001
From: Robbie Ko <robbieko(a)synology.com>
Date: Mon, 14 May 2018 10:51:34 +0800
Subject: [PATCH] Btrfs: send, fix invalid access to commit roots due to
concurrent snapshotting
[BUG]
btrfs incremental send BUG happens when creating a snapshot of snapshot
that is being used by send.
[REASON]
The problem can happen if while we are doing a send one of the snapshots
used (parent or send) is snapshotted, because snapshoting implies COWing
the root of the source subvolume/snapshot.
1. When doing an incremental send, the send process will get the commit
roots from the parent and send snapshots, and add references to them
through extent_buffer_get().
2. When a snapshot/subvolume is snapshotted, its root node is COWed
(transaction.c:create_pending_snapshot()).
3. COWing releases the space used by the node immediately, through:
__btrfs_cow_block()
--btrfs_free_tree_block()
----btrfs_add_free_space(bytenr of node)
4. Because send doesn't hold a transaction open, it's possible that
the transaction used to create the snapshot commits, switches the
commit root and the old space used by the previous root node gets
assigned to some other node allocation. Allocation of a new node will
use the existing extent buffer found in memory, which we previously
got a reference through extent_buffer_get(), and allow the extent
buffer's content (pages) to be modified:
btrfs_alloc_tree_block
--btrfs_reserve_extent
----find_free_extent (get bytenr of old node)
--btrfs_init_new_buffer (use bytenr of old node)
----btrfs_find_create_tree_block
------alloc_extent_buffer
--------find_extent_buffer (get old node)
5. So send can access invalid memory content and have unpredictable
behaviour.
[FIX]
So we fix the problem by copying the commit roots of the send and
parent snapshots and use those copies.
CallTrace looks like this:
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.c:1861!
invalid opcode: 0000 [#1] SMP
CPU: 6 PID: 24235 Comm: btrfs Tainted: P O 3.10.105 #23721
ffff88046652d680 ti: ffff88041b720000 task.ti: ffff88041b720000
RIP: 0010:[<ffffffffa08dd0e8>] read_node_slot+0x108/0x110 [btrfs]
RSP: 0018:ffff88041b723b68 EFLAGS: 00010246
RAX: ffff88043ca6b000 RBX: ffff88041b723c50 RCX: ffff880000000000
RDX: 000000000000004c RSI: ffff880314b133f8 RDI: ffff880458b24000
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff88041b723c66
R10: 0000000000000001 R11: 0000000000001000 R12: ffff8803f3e48890
R13: ffff8803f3e48880 R14: ffff880466351800 R15: 0000000000000001
FS: 00007f8c321dc8c0(0000) GS:ffff88047fcc0000(0000)
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
R2: 00007efd1006d000 CR3: 0000000213a24000 CR4: 00000000003407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff88041b723c50 ffff8803f3e48880 ffff8803f3e48890 ffff8803f3e48880
ffff880466351800 0000000000000001 ffffffffa08dd9d7 ffff88041b723c50
ffff8803f3e48880 ffff88041b723c66 ffffffffa08dde85 a9ff88042d2c4400
Call Trace:
[<ffffffffa08dd9d7>] ? tree_move_down.isra.33+0x27/0x50 [btrfs]
[<ffffffffa08dde85>] ? tree_advance+0xb5/0xc0 [btrfs]
[<ffffffffa08e83d4>] ? btrfs_compare_trees+0x2d4/0x760 [btrfs]
[<ffffffffa0982050>] ? finish_inode_if_needed+0x870/0x870 [btrfs]
[<ffffffffa09841ea>] ? btrfs_ioctl_send+0xeda/0x1050 [btrfs]
[<ffffffffa094bd3d>] ? btrfs_ioctl+0x1e3d/0x33f0 [btrfs]
[<ffffffff81111133>] ? handle_pte_fault+0x373/0x990
[<ffffffff8153a096>] ? atomic_notifier_call_chain+0x16/0x20
[<ffffffff81063256>] ? set_task_cpu+0xb6/0x1d0
[<ffffffff811122c3>] ? handle_mm_fault+0x143/0x2a0
[<ffffffff81539cc0>] ? __do_page_fault+0x1d0/0x500
[<ffffffff81062f07>] ? check_preempt_curr+0x57/0x90
[<ffffffff8115075a>] ? do_vfs_ioctl+0x4aa/0x990
[<ffffffff81034f83>] ? do_fork+0x113/0x3b0
[<ffffffff812dd7d7>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[<ffffffff81150cc8>] ? SyS_ioctl+0x88/0xa0
[<ffffffff8153e422>] ? system_call_fastpath+0x16/0x1b
---[ end trace 29576629ee80b2e1 ]---
Fixes: 7069830a9e38 ("Btrfs: add btrfs_compare_trees function")
CC: stable(a)vger.kernel.org # 3.6+
Signed-off-by: Robbie Ko <robbieko(a)synology.com>
Reviewed-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 3fd44835b386..63488f0b850f 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5414,12 +5414,24 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
down_read(&fs_info->commit_root_sem);
left_level = btrfs_header_level(left_root->commit_root);
left_root_level = left_level;
- left_path->nodes[left_level] = left_root->commit_root;
+ left_path->nodes[left_level] =
+ btrfs_clone_extent_buffer(left_root->commit_root);
+ if (!left_path->nodes[left_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(left_path->nodes[left_level]);
right_level = btrfs_header_level(right_root->commit_root);
right_root_level = right_level;
- right_path->nodes[right_level] = right_root->commit_root;
+ right_path->nodes[right_level] =
+ btrfs_clone_extent_buffer(right_root->commit_root);
+ if (!right_path->nodes[right_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(right_path->nodes[right_level]);
up_read(&fs_info->commit_root_sem);
The patch below does not apply to the 3.18-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 6f2f0b394b54e2b159ef969a0b5274e9bbf82ff2 Mon Sep 17 00:00:00 2001
From: Robbie Ko <robbieko(a)synology.com>
Date: Mon, 14 May 2018 10:51:34 +0800
Subject: [PATCH] Btrfs: send, fix invalid access to commit roots due to
concurrent snapshotting
[BUG]
btrfs incremental send BUG happens when creating a snapshot of snapshot
that is being used by send.
[REASON]
The problem can happen if while we are doing a send one of the snapshots
used (parent or send) is snapshotted, because snapshoting implies COWing
the root of the source subvolume/snapshot.
1. When doing an incremental send, the send process will get the commit
roots from the parent and send snapshots, and add references to them
through extent_buffer_get().
2. When a snapshot/subvolume is snapshotted, its root node is COWed
(transaction.c:create_pending_snapshot()).
3. COWing releases the space used by the node immediately, through:
__btrfs_cow_block()
--btrfs_free_tree_block()
----btrfs_add_free_space(bytenr of node)
4. Because send doesn't hold a transaction open, it's possible that
the transaction used to create the snapshot commits, switches the
commit root and the old space used by the previous root node gets
assigned to some other node allocation. Allocation of a new node will
use the existing extent buffer found in memory, which we previously
got a reference through extent_buffer_get(), and allow the extent
buffer's content (pages) to be modified:
btrfs_alloc_tree_block
--btrfs_reserve_extent
----find_free_extent (get bytenr of old node)
--btrfs_init_new_buffer (use bytenr of old node)
----btrfs_find_create_tree_block
------alloc_extent_buffer
--------find_extent_buffer (get old node)
5. So send can access invalid memory content and have unpredictable
behaviour.
[FIX]
So we fix the problem by copying the commit roots of the send and
parent snapshots and use those copies.
CallTrace looks like this:
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.c:1861!
invalid opcode: 0000 [#1] SMP
CPU: 6 PID: 24235 Comm: btrfs Tainted: P O 3.10.105 #23721
ffff88046652d680 ti: ffff88041b720000 task.ti: ffff88041b720000
RIP: 0010:[<ffffffffa08dd0e8>] read_node_slot+0x108/0x110 [btrfs]
RSP: 0018:ffff88041b723b68 EFLAGS: 00010246
RAX: ffff88043ca6b000 RBX: ffff88041b723c50 RCX: ffff880000000000
RDX: 000000000000004c RSI: ffff880314b133f8 RDI: ffff880458b24000
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff88041b723c66
R10: 0000000000000001 R11: 0000000000001000 R12: ffff8803f3e48890
R13: ffff8803f3e48880 R14: ffff880466351800 R15: 0000000000000001
FS: 00007f8c321dc8c0(0000) GS:ffff88047fcc0000(0000)
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
R2: 00007efd1006d000 CR3: 0000000213a24000 CR4: 00000000003407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
ffff88041b723c50 ffff8803f3e48880 ffff8803f3e48890 ffff8803f3e48880
ffff880466351800 0000000000000001 ffffffffa08dd9d7 ffff88041b723c50
ffff8803f3e48880 ffff88041b723c66 ffffffffa08dde85 a9ff88042d2c4400
Call Trace:
[<ffffffffa08dd9d7>] ? tree_move_down.isra.33+0x27/0x50 [btrfs]
[<ffffffffa08dde85>] ? tree_advance+0xb5/0xc0 [btrfs]
[<ffffffffa08e83d4>] ? btrfs_compare_trees+0x2d4/0x760 [btrfs]
[<ffffffffa0982050>] ? finish_inode_if_needed+0x870/0x870 [btrfs]
[<ffffffffa09841ea>] ? btrfs_ioctl_send+0xeda/0x1050 [btrfs]
[<ffffffffa094bd3d>] ? btrfs_ioctl+0x1e3d/0x33f0 [btrfs]
[<ffffffff81111133>] ? handle_pte_fault+0x373/0x990
[<ffffffff8153a096>] ? atomic_notifier_call_chain+0x16/0x20
[<ffffffff81063256>] ? set_task_cpu+0xb6/0x1d0
[<ffffffff811122c3>] ? handle_mm_fault+0x143/0x2a0
[<ffffffff81539cc0>] ? __do_page_fault+0x1d0/0x500
[<ffffffff81062f07>] ? check_preempt_curr+0x57/0x90
[<ffffffff8115075a>] ? do_vfs_ioctl+0x4aa/0x990
[<ffffffff81034f83>] ? do_fork+0x113/0x3b0
[<ffffffff812dd7d7>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[<ffffffff81150cc8>] ? SyS_ioctl+0x88/0xa0
[<ffffffff8153e422>] ? system_call_fastpath+0x16/0x1b
---[ end trace 29576629ee80b2e1 ]---
Fixes: 7069830a9e38 ("Btrfs: add btrfs_compare_trees function")
CC: stable(a)vger.kernel.org # 3.6+
Signed-off-by: Robbie Ko <robbieko(a)synology.com>
Reviewed-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 3fd44835b386..63488f0b850f 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5414,12 +5414,24 @@ int btrfs_compare_trees(struct btrfs_root *left_root,
down_read(&fs_info->commit_root_sem);
left_level = btrfs_header_level(left_root->commit_root);
left_root_level = left_level;
- left_path->nodes[left_level] = left_root->commit_root;
+ left_path->nodes[left_level] =
+ btrfs_clone_extent_buffer(left_root->commit_root);
+ if (!left_path->nodes[left_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(left_path->nodes[left_level]);
right_level = btrfs_header_level(right_root->commit_root);
right_root_level = right_level;
- right_path->nodes[right_level] = right_root->commit_root;
+ right_path->nodes[right_level] =
+ btrfs_clone_extent_buffer(right_root->commit_root);
+ if (!right_path->nodes[right_level]) {
+ up_read(&fs_info->commit_root_sem);
+ ret = -ENOMEM;
+ goto out;
+ }
extent_buffer_get(right_path->nodes[right_level]);
up_read(&fs_info->commit_root_sem);
The patch below does not apply to the 3.18-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 02a3307aa9c20b4f6626255b028f07f6cfa16feb Mon Sep 17 00:00:00 2001
From: Liu Bo <bo.liu(a)linux.alibaba.com>
Date: Wed, 16 May 2018 01:37:36 +0800
Subject: [PATCH] btrfs: fix reading stale metadata blocks after degraded raid1
mounts
If a btree block, aka. extent buffer, is not available in the extent
buffer cache, it'll be read out from the disk instead, i.e.
btrfs_search_slot()
read_block_for_search() # hold parent and its lock, go to read child
btrfs_release_path()
read_tree_block() # read child
Unfortunately, the parent lock got released before reading child, so
commit 5bdd3536cbbe ("Btrfs: Fix block generation verification race") had
used 0 as parent transid to read the child block. It forces
read_tree_block() not to check if parent transid is different with the
generation id of the child that it reads out from disk.
A simple PoC is included in btrfs/124,
0. A two-disk raid1 btrfs,
1. Right after mkfs.btrfs, block A is allocated to be device tree's root.
2. Mount this filesystem and put it in use, after a while, device tree's
root got COW but block A hasn't been allocated/overwritten yet.
3. Umount it and reload the btrfs module to remove both disks from the
global @fs_devices list.
4. mount -odegraded dev1 and write some data, so now block A is allocated
to be a leaf in checksum tree. Note that only dev1 has the latest
metadata of this filesystem.
5. Umount it and mount it again normally (with both disks), since raid1
can pick up one disk by the writer task's pid, if btrfs_search_slot()
needs to read block A, dev2 which does NOT have the latest metadata
might be read for block A, then we got a stale block A.
6. As parent transid is not checked, block A is marked as uptodate and
put into the extent buffer cache, so the future search won't bother
to read disk again, which means it'll make changes on this stale
one and make it dirty and flush it onto disk.
To avoid the problem, parent transid needs to be passed to
read_tree_block().
In order to get a valid parent transid, we need to hold the parent's
lock until finishing reading child.
This patch needs to be slightly adapted for stable kernels, the
&first_key parameter added to read_tree_block() is from 4.16+
(581c1760415c4). The fix is to replace 0 by 'gen'.
Fixes: 5bdd3536cbbe ("Btrfs: Fix block generation verification race")
CC: stable(a)vger.kernel.org # 4.4+
Signed-off-by: Liu Bo <bo.liu(a)linux.alibaba.com>
Reviewed-by: Filipe Manana <fdmanana(a)suse.com>
Reviewed-by: Qu Wenruo <wqu(a)suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 63488f0b850f..8c68961925b1 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2436,10 +2436,8 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
if (p->reada != READA_NONE)
reada_for_search(fs_info, p, level, slot, key->objectid);
- btrfs_release_path(p);
-
ret = -EAGAIN;
- tmp = read_tree_block(fs_info, blocknr, 0, parent_level - 1,
+ tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
&first_key);
if (!IS_ERR(tmp)) {
/*
@@ -2454,6 +2452,8 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
} else {
ret = PTR_ERR(tmp);
}
+
+ btrfs_release_path(p);
return ret;
}