From: Wang Hai <wanghai38(a)huawei.com>
Subject: mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook()
When I use kfree_rcu() to free a large memory allocated by kmalloc_node(),
the following dump occurs.
BUG: kernel NULL pointer dereference, address: 0000000000000020
[...]
Oops: 0000 [#1] SMP
[...]
Workqueue: events kfree_rcu_work
RIP: 0010:__obj_to_index include/linux/slub_def.h:182 [inline]
RIP: 0010:obj_to_index include/linux/slub_def.h:191 [inline]
RIP: 0010:memcg_slab_free_hook+0x120/0x260 mm/slab.h:363
[...]
Call Trace:
kmem_cache_free_bulk+0x58/0x630 mm/slub.c:3293
kfree_bulk include/linux/slab.h:413 [inline]
kfree_rcu_work+0x1ab/0x200 kernel/rcu/tree.c:3300
process_one_work+0x207/0x530 kernel/workqueue.c:2276
worker_thread+0x320/0x610 kernel/workqueue.c:2422
kthread+0x13d/0x160 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
When kmalloc_node() a large memory, page is allocated, not slab, so when
freeing memory via kfree_rcu(), this large memory should not be used by
memcg_slab_free_hook(), because memcg_slab_free_hook() is is used for
slab.
Using page_objcgs_check() instead of page_objcgs() in
memcg_slab_free_hook() to fix this bug.
Link: https://lkml.kernel.org/r/20210728145655.274476-1-wanghai38@huawei.com
Fixes: 270c6a71460e ("mm: memcontrol/slab: Use helpers to access slab page's memcg_data")
Signed-off-by: Wang Hai <wanghai38(a)huawei.com>
Reviewed-by: Shakeel Butt <shakeelb(a)google.com>
Acked-by: Michal Hocko <mhocko(a)suse.com>
Acked-by: Roman Gushchin <guro(a)fb.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang(a)huawei.com>
Reviewed-by: Muchun Song <songmuchun(a)bytedance.com>
Cc: Christoph Lameter <cl(a)linux.com>
Cc: Pekka Enberg <penberg(a)kernel.org>
Cc: David Rientjes <rientjes(a)google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim(a)lge.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Alexei Starovoitov <ast(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/slab.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/slab.h~mm-memcg-fix-null-pointer-dereference-in-memcg_slab_free_hook
+++ a/mm/slab.h
@@ -346,7 +346,7 @@ static inline void memcg_slab_free_hook(
continue;
page = virt_to_head_page(p[i]);
- objcgs = page_objcgs(page);
+ objcgs = page_objcgs_check(page);
if (!objcgs)
continue;
_
From: Johannes Weiner <hannes(a)cmpxchg.org>
Subject: mm: memcontrol: fix blocking rstat function called from atomic cgroup1 thresholding code
Dan Carpenter reports:
The patch 2d146aa3aa84: "mm: memcontrol: switch to rstat" from Apr
29, 2021, leads to the following static checker warning:
kernel/cgroup/rstat.c:200 cgroup_rstat_flush()
warn: sleeping in atomic context
mm/memcontrol.c
3572 static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
3573 {
3574 unsigned long val;
3575
3576 if (mem_cgroup_is_root(memcg)) {
3577 cgroup_rstat_flush(memcg->css.cgroup);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is from static analysis and potentially a false positive. The
problem is that mem_cgroup_usage() is called from __mem_cgroup_threshold()
which holds an rcu_read_lock(). And the cgroup_rstat_flush() function
can sleep.
3578 val = memcg_page_state(memcg, NR_FILE_PAGES) +
3579 memcg_page_state(memcg, NR_ANON_MAPPED);
3580 if (swap)
3581 val += memcg_page_state(memcg, MEMCG_SWAP);
3582 } else {
3583 if (!swap)
3584 val = page_counter_read(&memcg->memory);
3585 else
3586 val = page_counter_read(&memcg->memsw);
3587 }
3588 return val;
3589 }
__mem_cgroup_threshold() indeed holds the rcu lock. In addition, the
thresholding code is invoked during stat changes, and those contexts have
irqs disabled as well. If the lock breaking occurs inside the flush
function, it will result in a sleep from an atomic context.
Use the irqsafe flushing variant in mem_cgroup_usage() to fix this.
Link: https://lkml.kernel.org/r/20210726150019.251820-1-hannes@cmpxchg.org
Fixes: 2d146aa3aa84 ("mm: memcontrol: switch to rstat")
Signed-off-by: Johannes Weiner <hannes(a)cmpxchg.org>
Reported-by: Dan Carpenter <dan.carpenter(a)oracle.com>
Acked-by: Chris Down <chris(a)chrisdown.name>
Reviewed-by: Rik van Riel <riel(a)surriel.com>
Acked-by: Michal Hocko <mhocko(a)suse.com>
Reviewed-by: Shakeel Butt <shakeelb(a)google.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/memcontrol.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/memcontrol.c~mm-memcontrol-fix-blocking-rstat-function-called-from-atomic-cgroup1-thresholding-code
+++ a/mm/memcontrol.c
@@ -3574,7 +3574,8 @@ static unsigned long mem_cgroup_usage(st
unsigned long val;
if (mem_cgroup_is_root(memcg)) {
- cgroup_rstat_flush(memcg->css.cgroup);
+ /* mem_cgroup_threshold() calls here from irqsafe context */
+ cgroup_rstat_flush_irqsafe(memcg->css.cgroup);
val = memcg_page_state(memcg, NR_FILE_PAGES) +
memcg_page_state(memcg, NR_ANON_MAPPED);
if (swap)
_
From: Junxiao Bi <junxiao.bi(a)oracle.com>
Subject: ocfs2: issue zeroout to EOF blocks
For punch holes in EOF blocks, fallocate used buffer write to zero the EOF
blocks in last cluster. But since ->writepage will ignore EOF pages,
those zeros will not be flushed.
This "looks" ok as commit 6bba4471f0cc ("ocfs2: fix data corruption by
fallocate") will zero the EOF blocks when extend the file size, but it
isn't. The problem happened on those EOF pages, before writeback, those
pages had DIRTY flag set and all buffer_head in them also had DIRTY flag
set, when writeback run by write_cache_pages(), DIRTY flag on the page was
cleared, but DIRTY flag on the buffer_head not.
When next write happened to those EOF pages, since buffer_head already had
DIRTY flag set, it would not mark page DIRTY again. That made writeback
ignore them forever. That will cause data corruption. Even directio
write can't work because it will fail when trying to drop pages caches
before direct io, as it found the buffer_head for those pages still had
DIRTY flag set, then it will fall back to buffer io mode.
To make a summary of the issue, as writeback ingores EOF pages, once any
EOF page is generated, any write to it will only go to the page cache, it
will never be flushed to disk even file size extends and that page is not
EOF page any more. The fix is to avoid zero EOF blocks with buffer write.
The following code snippet from qemu-img could trigger the corruption.
656 open("6b3711ae-3306-4bdd-823c-cf1c0060a095.conv.2", O_RDWR|O_DIRECT|O_CLOEXEC) = 11
...
660 fallocate(11, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, 2275868672, 327680 <unfinished ...>
660 fallocate(11, 0, 2275868672, 327680) = 0
658 pwrite64(11, "
Link: https://lkml.kernel.org/r/20210722054923.24389-2-junxiao.bi@oracle.com
Signed-off-by: Junxiao Bi <junxiao.bi(a)oracle.com>
Reviewed-by: Joseph Qi <joseph.qi(a)linux.alibaba.com>
Cc: Mark Fasheh <mark(a)fasheh.com>
Cc: Joel Becker <jlbec(a)evilplan.org>
Cc: Changwei Ge <gechangwei(a)live.cn>
Cc: Gang He <ghe(a)suse.com>
Cc: Jun Piao <piaojun(a)huawei.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/ocfs2/file.c | 99 +++++++++++++++++++++++++++-------------------
1 file changed, 60 insertions(+), 39 deletions(-)
--- a/fs/ocfs2/file.c~ocfs2-issue-zeroout-to-eof-blocks
+++ a/fs/ocfs2/file.c
@@ -1529,6 +1529,45 @@ static void ocfs2_truncate_cluster_pages
}
}
+/*
+ * zero out partial blocks of one cluster.
+ *
+ * start: file offset where zero starts, will be made upper block aligned.
+ * len: it will be trimmed to the end of current cluster if "start + len"
+ * is bigger than it.
+ */
+static int ocfs2_zeroout_partial_cluster(struct inode *inode,
+ u64 start, u64 len)
+{
+ int ret;
+ u64 start_block, end_block, nr_blocks;
+ u64 p_block, offset;
+ u32 cluster, p_cluster, nr_clusters;
+ struct super_block *sb = inode->i_sb;
+ u64 end = ocfs2_align_bytes_to_clusters(sb, start);
+
+ if (start + len < end)
+ end = start + len;
+
+ start_block = ocfs2_blocks_for_bytes(sb, start);
+ end_block = ocfs2_blocks_for_bytes(sb, end);
+ nr_blocks = end_block - start_block;
+ if (!nr_blocks)
+ return 0;
+
+ cluster = ocfs2_bytes_to_clusters(sb, start);
+ ret = ocfs2_get_clusters(inode, cluster, &p_cluster,
+ &nr_clusters, NULL);
+ if (ret)
+ return ret;
+ if (!p_cluster)
+ return 0;
+
+ offset = start_block - ocfs2_clusters_to_blocks(sb, cluster);
+ p_block = ocfs2_clusters_to_blocks(sb, p_cluster) + offset;
+ return sb_issue_zeroout(sb, p_block, nr_blocks, GFP_NOFS);
+}
+
static int ocfs2_zero_partial_clusters(struct inode *inode,
u64 start, u64 len)
{
@@ -1538,6 +1577,7 @@ static int ocfs2_zero_partial_clusters(s
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
unsigned int csize = osb->s_clustersize;
handle_t *handle;
+ loff_t isize = i_size_read(inode);
/*
* The "start" and "end" values are NOT necessarily part of
@@ -1558,6 +1598,26 @@ static int ocfs2_zero_partial_clusters(s
if ((start & (csize - 1)) == 0 && (end & (csize - 1)) == 0)
goto out;
+ /* No page cache for EOF blocks, issue zero out to disk. */
+ if (end > isize) {
+ /*
+ * zeroout eof blocks in last cluster starting from
+ * "isize" even "start" > "isize" because it is
+ * complicated to zeroout just at "start" as "start"
+ * may be not aligned with block size, buffer write
+ * would be required to do that, but out of eof buffer
+ * write is not supported.
+ */
+ ret = ocfs2_zeroout_partial_cluster(inode, isize,
+ end - isize);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+ if (start >= isize)
+ goto out;
+ end = isize;
+ }
handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
@@ -1856,45 +1916,6 @@ out:
}
/*
- * zero out partial blocks of one cluster.
- *
- * start: file offset where zero starts, will be made upper block aligned.
- * len: it will be trimmed to the end of current cluster if "start + len"
- * is bigger than it.
- */
-static int ocfs2_zeroout_partial_cluster(struct inode *inode,
- u64 start, u64 len)
-{
- int ret;
- u64 start_block, end_block, nr_blocks;
- u64 p_block, offset;
- u32 cluster, p_cluster, nr_clusters;
- struct super_block *sb = inode->i_sb;
- u64 end = ocfs2_align_bytes_to_clusters(sb, start);
-
- if (start + len < end)
- end = start + len;
-
- start_block = ocfs2_blocks_for_bytes(sb, start);
- end_block = ocfs2_blocks_for_bytes(sb, end);
- nr_blocks = end_block - start_block;
- if (!nr_blocks)
- return 0;
-
- cluster = ocfs2_bytes_to_clusters(sb, start);
- ret = ocfs2_get_clusters(inode, cluster, &p_cluster,
- &nr_clusters, NULL);
- if (ret)
- return ret;
- if (!p_cluster)
- return 0;
-
- offset = start_block - ocfs2_clusters_to_blocks(sb, cluster);
- p_block = ocfs2_clusters_to_blocks(sb, p_cluster) + offset;
- return sb_issue_zeroout(sb, p_block, nr_blocks, GFP_NOFS);
-}
-
-/*
* Parts of this function taken from xfs_change_file_space()
*/
static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
_
From: Junxiao Bi <junxiao.bi(a)oracle.com>
Subject: ocfs2: fix zero out valid data
If append-dio feature is enabled, direct-io write and fallocate could run
in parallel to extend file size, fallocate used "orig_isize" to record
i_size before taking "ip_alloc_sem", when ocfs2_zeroout_partial_cluster()
zeroout EOF blocks, i_size maybe already extended by
ocfs2_dio_end_io_write(), that will cause valid data zeroed out.
Link: https://lkml.kernel.org/r/20210722054923.24389-1-junxiao.bi@oracle.com
Fixes: 6bba4471f0cc ("ocfs2: fix data corruption by fallocate")
Signed-off-by: Junxiao Bi <junxiao.bi(a)oracle.com>
Reviewed-by: Joseph Qi <joseph.qi(a)linux.alibaba.com>
Cc: Changwei Ge <gechangwei(a)live.cn>
Cc: Gang He <ghe(a)suse.com>
Cc: Joel Becker <jlbec(a)evilplan.org>
Cc: Jun Piao <piaojun(a)huawei.com>
Cc: Mark Fasheh <mark(a)fasheh.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/ocfs2/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/ocfs2/file.c~ocfs2-fix-zero-out-valid-data
+++ a/fs/ocfs2/file.c
@@ -1935,7 +1935,6 @@ static int __ocfs2_change_file_space(str
goto out_inode_unlock;
}
- orig_isize = i_size_read(inode);
switch (sr->l_whence) {
case 0: /*SEEK_SET*/
break;
@@ -1943,7 +1942,7 @@ static int __ocfs2_change_file_space(str
sr->l_start += f_pos;
break;
case 2: /*SEEK_END*/
- sr->l_start += orig_isize;
+ sr->l_start += i_size_read(inode);
break;
default:
ret = -EINVAL;
@@ -1998,6 +1997,7 @@ static int __ocfs2_change_file_space(str
ret = -EINVAL;
}
+ orig_isize = i_size_read(inode);
/* zeroout eof blocks in the cluster. */
if (!ret && change_size && orig_isize < size) {
ret = ocfs2_zeroout_partial_cluster(inode, orig_isize,
_