Re: [PATCH] mm/mempool: warn about __GFP_ZERO usage

[Andrew Morton]

On Wed, 16 Apr 2014 14:15:56 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> @@ -201,7 +201,9 @@ void * mempool_alloc(mempool_t *pool, gf
>  	wait_queue_t wait;
>  	gfp_t gfp_temp;
>  
> -	VM_BUG_ON(gfp_mask & __GFP_ZERO);
> +#ifdef CONFIG_DEBUG_VM
> +	WARN_ON_ONCE(gfp_mask & __GFP_ZERO);	/* Where's VM_WARN_ON_ONCE()? */
> +#endif

bah, don't be lazy.

From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: include/linux/mmdebug.h: add VM_WARN_ON() and VM_WARN_ON_ONCE()

WARN_ON() and WARN_ON_ONCE(), dependent on CONFIG_DEBUG_VM

Cc: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/mmdebug.h |    4 ++++
 1 file changed, 4 insertions(+)

diff -puN include/linux/mmdebug.h~include-linux-mmdebugh-add-vm_warn_on-and-vm_warn_on_once include/linux/mmdebug.h
--- a/include/linux/mmdebug.h~include-linux-mmdebugh-add-vm_warn_on-and-vm_warn_on_once
+++ a/include/linux/mmdebug.h
@@ -11,9 +11,13 @@ extern void dump_page_badflags(struct pa
 #define VM_BUG_ON(cond) BUG_ON(cond)
 #define VM_BUG_ON_PAGE(cond, page) \
 	do { if (unlikely(cond)) { dump_page(page, NULL); BUG(); } } while (0)
+#define VM_WARN_ON(cond) WARN_ON(cond)
+#define VM_WARN_ON_ONCE(cond) WARN_ON_ONCE(cond)
 #else
 #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
+#define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
+#define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
 #endif
 
 #ifdef CONFIG_DEBUG_VIRTUAL
_

From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm-mempool-warn-about-__gfp_zero-usage-fix

use VM_WARN_ON_ONCE

Cc: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/mempool.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN mm/mempool.c~mm-mempool-warn-about-__gfp_zero-usage-fix mm/mempool.c
--- a/mm/mempool.c~mm-mempool-warn-about-__gfp_zero-usage-fix
+++ a/mm/mempool.c
@@ -201,7 +201,7 @@ void * mempool_alloc(mempool_t *pool, gf
 	wait_queue_t wait;
 	gfp_t gfp_temp;
 
-	VM_BUG_ON(gfp_mask & __GFP_ZERO);
+	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
 	might_sleep_if(gfp_mask & __GFP_WAIT);
 
 	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */
_

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