Thread (12 messages) 12 messages, 5 authors, 2016-05-23

Re: [PATCH] mm/zsmalloc: don't fail if can't create debugfs info

From: Ganesh Mahendran <hidden>
Date: 2016-05-03 02:18:07
Also in: lkml

Hello, Dan:

2016-04-28 23:36 GMT+08:00 Dan Streetman [off-list ref]:
quoted hunk ↗ jump to hunk
Change the return type of zs_pool_stat_create() to void, and
remove the logic to abort pool creation if the stat debugfs
dir/file could not be created.

The debugfs stat file is for debugging/information only, and doesn't
affect operation of zsmalloc; there is no reason to abort creating
the pool if the stat file can't be created.  This was seen with
zswap, which used the same name for all pool creations, which caused
zsmalloc to fail to create a second pool for zswap if
CONFIG_ZSMALLOC_STAT was enabled.

Cc: Dan Streetman <redacted>
Signed-off-by: Dan Streetman <redacted>
---
 mm/zsmalloc.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e72efb1..25a7db2 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -567,17 +567,17 @@ static const struct file_operations zs_stat_size_ops = {
        .release        = single_release,
 };

-static int zs_pool_stat_create(const char *name, struct zs_pool *pool)
+static void zs_pool_stat_create(const char *name, struct zs_pool *pool)
 {
        struct dentry *entry;

        if (!zs_stat_root)
-               return -ENODEV;
+               return;
Since the error will not be propagated, Would it be better if you
add some pr_warn information here(also in zs_stat_init() if you
send your V2 patch as Minchan suggested)? It will be useful for
developers to know the reason of failed to create debugfs file/dir.

Thanks.
quoted hunk ↗ jump to hunk
        entry = debugfs_create_dir(name, zs_stat_root);
        if (!entry) {
                pr_warn("debugfs dir <%s> creation failed\n", name);
-               return -ENOMEM;
+               return;
        }
        pool->stat_dentry = entry;
@@ -586,10 +586,8 @@ static int zs_pool_stat_create(const char *name, struct zs_pool *pool)
        if (!entry) {
                pr_warn("%s: debugfs file entry <%s> creation failed\n",
                                name, "classes");
-               return -ENOMEM;
+               return;
        }
-
-       return 0;
 }

 static void zs_pool_stat_destroy(struct zs_pool *pool)
@@ -607,9 +605,8 @@ static void __exit zs_stat_exit(void)
 {
 }

-static inline int zs_pool_stat_create(const char *name, struct zs_pool *pool)
+static inline void zs_pool_stat_create(const char *name, struct zs_pool *pool)
 {
-       return 0;
 }

 static inline void zs_pool_stat_destroy(struct zs_pool *pool)
@@ -1956,8 +1953,8 @@ struct zs_pool *zs_create_pool(const char *name, gfp_t flags)

        pool->flags = flags;

-       if (zs_pool_stat_create(name, pool))
-               goto err;
+       /* debug only, don't abort if it fails */
+       zs_pool_stat_create(name, pool);

        /*
         * Not critical, we still can use the pool
--
2.7.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help