[Devel] [PATCH vz7 v2 1/2] nfsd: more robust allocation failure handling in nfsd_reply_cache_init

[Oleg Babin]

From: Jeff Layton <jlayton at redhat.com>

Currently, we try to allocate the cache as a single, large chunk, which
can fail if no big chunks of memory are available. We _do_ try to size
it according to the amount of memory in the box, but if the server is
started well after boot time, then the allocation can fail due to memory
fragmentation.

Fall back to doing a vzalloc if the kcalloc fails, and switch the
shutdown code to do a kvfree to handle freeing correctly.

Reported-by: Olaf Hering <olaf at aepfle.de>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Jeff Layton <jlayton at redhat.com>
Signed-off-by: J. Bruce Fields <bfields at redhat.com>

ms commit 8f97514b423a0983e4c600099882a9c6613142d2

https://jira.sw.ru/browse/PSBM-84234
Signed-off-by: Oleg Babin <obabin at virtuozzo.com>
---
 fs/nfsd/nfscache.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index a4fa08e..b5c25ea 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 #include <linux/sunrpc/addr.h>
 #include <linux/highmem.h>
 #include <linux/log2.h>
@@ -178,8 +179,12 @@ int nfsd_reply_cache_init(void)
 		goto out_nomem;
 
 	drc_hashtbl = kcalloc(hashsize, sizeof(*drc_hashtbl), GFP_KERNEL);
-	if (!drc_hashtbl)
-		goto out_nomem;
+	if (!drc_hashtbl) {
+		drc_hashtbl = vzalloc(hashsize * sizeof(*drc_hashtbl));
+		if (!drc_hashtbl)
+			goto out_nomem;
+	}
+
 	for (i = 0; i < hashsize; i++) {
 		INIT_LIST_HEAD(&drc_hashtbl[i].lru_head);
 		spin_lock_init(&drc_hashtbl[i].cache_lock);
@@ -209,7 +214,7 @@ void nfsd_reply_cache_shutdown(void)
 		}
 	}
 
-	kfree (drc_hashtbl);
+	kvfree(drc_hashtbl);
 	drc_hashtbl = NULL;
 	drc_hashsize = 0;
 
-- 
1.8.3.1