Even if __vmalloc() receives GFP_NOFS, this function allocates
data pages and auxiliary structures (e.g. pagetables) with __GFP_FS[1].
To prevent memory reclaim from re-entering the filesystem here and
potentially deadlocking, use memalloc_nofs_save() that gets
__vmalloc() to drop __GFP_FS.
[1] linux-tree/Documentation/core-api/gfp-mask-fs-io.rst
Signed-off-by: Naoto Kobayashi <naoto.kobayashi4c@xxxxxxxxx>
---
fs/ext4/super.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e8965aa6ecce..7f4c9a43a3f3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -43,6 +43,7 @@
#include <linux/uaccess.h>
#include <linux/iversion.h>
#include <linux/unicode.h>
+#include <linux/sched/mm.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
@@ -206,11 +207,13 @@ void ext4_superblock_csum_set(struct super_block *sb)
void *ext4_kvmalloc_nofs(size_t size)
{
+ unsigned int nofs_flag;
void *ret;
- ret = kmalloc(size, GFP_NOFS | __GFP_NOWARN);
- if (!ret)
- ret = __vmalloc(size, GFP_NOFS, PAGE_KERNEL);
+ /* kvmalloc() does not support GFP_NOFS */
+ nofs_flag = memalloc_nofs_save();
+ ret = kvmalloc(size, GFP_KERNEL);
+ memalloc_nofs_restore(nofs_flag);
return ret;
}
--
2.16.6
