Messages in this thread | | | Date | Wed, 11 May 2022 13:12:55 +0800 | Subject | Re: [PATCH 1/2] mm: fix missing handler for __GFP_NOWARN | From | Qi Zheng <> |
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On 2022/5/10 7:38 PM, Qi Zheng 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.
Hi Andrew,
Maybe we only need to deal with memory allocation failures, such as should_fail() (This leads to deadlock in PATCH[2/2]). These WARN_ON_ONCE()s report usage problems and should not be printed. If they are printed, we should fix these usage problems.
Thanks, Qi
> > Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> > --- > include/linux/fault-inject.h | 2 ++ > lib/fault-inject.c | 3 +++ > mm/failslab.c | 3 +++ > mm/internal.h | 11 +++++++++++ > mm/page_alloc.c | 22 ++++++++++++---------- > 5 files changed, 31 insertions(+), 10 deletions(-) > > diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h > index 2d04f6448cde..9f6e25467844 100644 > --- a/include/linux/fault-inject.h > +++ b/include/linux/fault-inject.h > @@ -20,6 +20,7 @@ struct fault_attr { > atomic_t space; > unsigned long verbose; > bool task_filter; > + bool no_warn; > unsigned long stacktrace_depth; > unsigned long require_start; > unsigned long require_end; > @@ -39,6 +40,7 @@ struct fault_attr { > .ratelimit_state = RATELIMIT_STATE_INIT_DISABLED, \ > .verbose = 2, \ > .dname = NULL, \ > + .no_warn = false, \ > } > > #define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER > diff --git a/lib/fault-inject.c b/lib/fault-inject.c > index ce12621b4275..423784d9c058 100644 > --- a/lib/fault-inject.c > +++ b/lib/fault-inject.c > @@ -41,6 +41,9 @@ EXPORT_SYMBOL_GPL(setup_fault_attr); > > static void fail_dump(struct fault_attr *attr) > { > + if (attr->no_warn) > + return; > + > if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { > printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" > "name %pd, interval %lu, probability %lu, " > diff --git a/mm/failslab.c b/mm/failslab.c > index f92fed91ac23..58df9789f1d2 100644 > --- a/mm/failslab.c > +++ b/mm/failslab.c > @@ -30,6 +30,9 @@ bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags) > if (failslab.cache_filter && !(s->flags & SLAB_FAILSLAB)) > return false; > > + if (gfpflags & __GFP_NOWARN) > + failslab.attr.no_warn = true; > + > return should_fail(&failslab.attr, s->object_size); > } > > diff --git a/mm/internal.h b/mm/internal.h > index cf16280ce132..7a268fac6559 100644 > --- 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); \ > +}) > + > void page_writeback_init(void); > > static inline void *folio_raw_mapping(struct folio *folio) > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0e42038382c1..2bf4ce4d0e2f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3722,7 +3722,7 @@ struct page *rmqueue(struct zone *preferred_zone, > * We most definitely don't want callers attempting to > * allocate greater than order-1 page units with __GFP_NOFAIL. > */ > - WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1)); > + WARN_ON_ONCE_GFP((gfp_flags & __GFP_NOFAIL) && (order > 1), gfp_flags); > > do { > page = NULL; > @@ -3799,6 +3799,9 @@ static bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) > (gfp_mask & __GFP_DIRECT_RECLAIM)) > return false; > > + if (gfp_mask & __GFP_NOWARN) > + fail_page_alloc.attr.no_warn = true; > + > return should_fail(&fail_page_alloc.attr, 1 << order); > } > > @@ -4346,7 +4349,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, > */ > > /* Exhausted what can be done so it's blame time */ > - if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) { > + if (out_of_memory(&oc) || > + WARN_ON_ONCE_GFP(gfp_mask & __GFP_NOFAIL, gfp_mask)) { > *did_some_progress = 1; > > /* > @@ -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: > @@ -5117,7 +5121,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * All existing users of the __GFP_NOFAIL are blockable, so warn > * of any new users that actually require GFP_NOWAIT > */ > - if (WARN_ON_ONCE(!can_direct_reclaim)) > + if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask)) > goto fail; > > /* > @@ -5125,7 +5129,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * because we cannot reclaim anything and only can loop waiting > * for somebody to do a work for us > */ > - WARN_ON_ONCE(current->flags & PF_MEMALLOC); > + WARN_ON_ONCE_GFP(current->flags & PF_MEMALLOC, gfp_mask); > > /* > * non failing costly orders are a hard requirement which we > @@ -5133,7 +5137,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * so that we can identify them and convert them to something > * else. > */ > - WARN_ON_ONCE(order > PAGE_ALLOC_COSTLY_ORDER); > + WARN_ON_ONCE_GFP(order > PAGE_ALLOC_COSTLY_ORDER, gfp_mask); > > /* > * Help non-failing allocations by giving them access to memory > @@ -5379,10 +5383,8 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, > * There are several places where we assume that the order value is sane > * so bail out early if the request is out of bound. > */ > - if (unlikely(order >= MAX_ORDER)) { > - WARN_ON_ONCE(!(gfp & __GFP_NOWARN)); > + if (WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp)) > return NULL; > - } > > gfp &= gfp_allowed_mask; > /*
-- Thanks, Qi
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