From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
writebacks can recurse into itself under low memory situations.
Set memalloc_nofs_save() in order to make sure it does not
recurse.
Since writeouts are performed for fdatawrites as well, set
memalloc_nofs_save while performing fdatawrites.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/fs-writeback.c | 8 ++++++++
fs/xfs/xfs_aops.c | 7 -------
mm/filemap.c | 3 +++
3 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d4d04fee568a..42f7f4c2063b 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -28,6 +28,7 @@
#include <linux/tracepoint.h>
#include <linux/device.h>
#include <linux/memcontrol.h>
+#include <linux/sched/mm.h>
#include "internal.h"
/*
@@ -1713,7 +1714,12 @@ static long wb_writeback(struct bdi_writeback *wb,
struct inode *inode;
long progress;
struct blk_plug plug;
+ unsigned flags;
+ if (current->flags & PF_MEMALLOC_NOFS)
+ return 0;
+
+ flags = memalloc_nofs_save();
oldest_jif = jiffies;
work->older_than_this = &oldest_jif;
@@ -1797,6 +1803,8 @@ static long wb_writeback(struct bdi_writeback *wb,
spin_unlock(&wb->list_lock);
blk_finish_plug(&plug);
+ memalloc_nofs_restore(flags);
+
return nr_pages - work->nr_pages;
}
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 9c6a830da0ee..943ade03489a 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1086,13 +1086,6 @@ xfs_do_writepage(
PF_MEMALLOC))
goto redirty;
- /*
- * Given that we do not allow direct reclaim to call us, we should
- * never be called while in a filesystem transaction.
- */
- if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
- goto redirty;
-
/*
* Is this page beyond the end of the file?
*
diff --git a/mm/filemap.c b/mm/filemap.c
index 693f62212a59..3c9ead9a1e32 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -430,6 +430,7 @@ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
loff_t end, int sync_mode)
{
int ret;
+ unsigned flags;
struct writeback_control wbc = {
.sync_mode = sync_mode,
.nr_to_write = LONG_MAX,
@@ -440,9 +441,11 @@ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
if (!mapping_cap_writeback_dirty(mapping))
return 0;
+ flags = memalloc_nofs_save();
wbc_attach_fdatawrite_inode(&wbc, mapping->host);
ret = do_writepages(mapping, &wbc);
wbc_detach_inode(&wbc);
+ memalloc_nofs_restore(flags);
return ret;
}
--
2.16.2
