Messages in this thread Patch in this message | | | Date | Wed, 11 May 2022 13:28:53 +0800 | Subject | Re: [PATCH 1/2] mm: fix missing handler for __GFP_NOWARN | From | Qi Zheng <> |
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On 2022/5/11 1:12 PM, Qi Zheng wrote: > > > 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
such as WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1), gfp_flags).
> 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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