On 2022/5/11 2:59 AM, Andrew Morton wrote:
On Tue, 10 May 2022 19:38:08 +0800 Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
We expect no warnings to be issued when we specify __GFP_NOWARN, but
currently in paths like alloc_pages() and kmalloc(), there are still
some warnings printed, fix it.
Looks sane to me.
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -35,6 +35,17 @@ struct folio_batch;
/* Do not use these with a slab allocator */
#define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK)
+#define WARN_ON_ONCE_GFP(cond, gfp) ({ \
+ static bool __section(".data.once") __warned; \
+ int __ret_warn_once = !!(cond); \
+ \
+ if (unlikely(!(gfp & __GFP_NOWARN) && __ret_warn_once && !__warned)) { \
+ __warned = true; \
+ WARN_ON(1); \
+ } \
+ unlikely(__ret_warn_once); \
+})
I don't think WARN_ON_ONCE_GFP is a good name for this. But
WARN_ON_ONCE_IF_NOT_GFP_NOWARN is too long :(
WARN_ON_ONCE_NOWARN might be better. No strong opinion here, really.
I've thought about WARN_ON_ONCE_NOWARN, but I feel a little weird
putting 'WARN' and 'NOWARN' together, how about WARN_ON_ONCE_IF_ALLOWED?
@@ -4902,8 +4906,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
* We also sanity check to catch abuse of atomic reserves being used by
* callers that are not in atomic context.
*/
- if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
- (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)))
+ if (WARN_ON_ONCE_GFP((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) ==
+ (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM), gfp_mask))
gfp_mask &= ~__GFP_ATOMIC;
retry_cpuset:
I dropped this hunk - Neil's "mm: discard __GFP_ATOMIC"
(https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@xxxxxxxxxxxxxxxxxxxxx)
deleted this code.
This series is based on v5.18-rc5, I will rebase it to the latest next
branch and check if there are any missing WARN_ON_ONCEs that are not
being handled.
Thanks,
Qi
--
Thanks,
Qi
