[PATCH 16/19] VFS: use GFP_NOFS rather than GFP_KERNEL in __d_alloc.

From: NeilBrown
Date: Wed Apr 16 2014 - 00:19:57 EST


__d_alloc can be called with i_mutex held, so it is safer to
use GFP_NOFS.

lockdep reports this can deadlock when loop-back NFS is in use,
as nfsd may be required to write out for reclaim, and nfsd certainly
takes i_mutex.

Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
fs/dcache.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index ca02c13a84aa..3651ff6185b4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1483,7 +1483,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
struct dentry *dentry;
char *dname;

- dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
+ dentry = kmem_cache_alloc(dentry_cache, GFP_NOFS);
if (!dentry)
return NULL;

@@ -1495,7 +1495,7 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
*/
dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
if (name->len > DNAME_INLINE_LEN-1) {
- dname = kmalloc(name->len + 1, GFP_KERNEL);
+ dname = kmalloc(name->len + 1, GFP_NOFS);
if (!dname) {
kmem_cache_free(dentry_cache, dentry);
return NULL;


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