Messages in this thread | | | Date | Wed, 18 Jan 2017 11:10:06 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH 2/4] mm, page_alloc: warn_alloc print nodemask |
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On Tue 17-01-17 15:01:35, David Rientjes wrote: > On Tue, 17 Jan 2017, Michal Hocko wrote: > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 57dc3c3b53c1..3e35eb04a28a 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -1912,8 +1912,8 @@ extern void si_meminfo_node(struct sysinfo *val, int nid); > > extern unsigned long arch_reserved_kernel_pages(void); > > #endif > > > > -extern __printf(2, 3) > > -void warn_alloc(gfp_t gfp_mask, const char *fmt, ...); > > +extern __printf(3, 4) > > +void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...); > > > > extern void setup_per_cpu_pageset(void); > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 8f4f306d804c..7f9c0ee18ae0 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -3031,12 +3031,13 @@ static void warn_alloc_show_mem(gfp_t gfp_mask) > > show_mem(filter); > > } > > > > -void warn_alloc(gfp_t gfp_mask, const char *fmt, ...) > > +void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...) > > { > > struct va_format vaf; > > va_list args; > > static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL, > > DEFAULT_RATELIMIT_BURST); > > + nodemask_t *nm = (nodemask) ? nodemask : &cpuset_current_mems_allowed; > > Small nit: wouldn't it be helpful to know if ac->nodemask is actually NULL > rather than setting it to cpuset_current_mems_allowed here? We know the > effective nodemask from cpuset_print_current_mems_allowed(), but we don't > know if there's a bug in the page allocator which is failing to set > ac->nodemask appropriately if we blindly set it here when cpusets are not > enabled.
You are right that games with the nodemask are dangerous and can potentially lead to unexpected behavior. I wanted to make this code as simple as possible though and printing mems_allowed for NULL nodemask looked like the way. Feel free to post a patch to handle null nodemask in the output if you think it is an improvement.
-- Michal Hocko SUSE Labs
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