On Wed, 11 May 2022 10:19:48 +0800 Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
>
> ,,,
> >> --- 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?
I dunno. WARN_ON_ONCE_GFP isn't too bad I suppose. Add a comment over
the definition explaining it?
> >
> >> @@ -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.
Against git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm branch
mm-unstable, please. That ends up in linux-next, with a delay.
