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Tue, 05 Oct 2021 14:20:20 -0700 (PDT) Received: from [192.168.1.116] ([66.219.217.159]) by smtp.gmail.com with ESMTPSA id b11sm6006843ile.12.2021.10.05.14.20.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Oct 2021 14:20:20 -0700 (PDT) Subject: Re: [PATCH] mm: don't call should_failslab() for !CONFIG_FAILSLAB To: Andrew Morton Cc: LKML , Linux Memory Management List References: <20211005141832.d6f3d4e06c4ad7a06cd554dd@linux-foundation.org> From: Jens Axboe Message-ID: <316ad54a-67e9-879d-c406-6a4a606924aa@kernel.dk> Date: Tue, 5 Oct 2021 15:20:18 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20211005141832.d6f3d4e06c4ad7a06cd554dd@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 2A2469001352 X-Stat-Signature: aeobej3duqon74tg5q56shcbmqkfzex8 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel-dk.20210112.gappssmtp.com header.s=20210112 header.b=5gAjizCN; dmarc=none; spf=pass (imf28.hostedemail.com: domain of axboe@kernel.dk designates 209.85.166.180 as permitted sender) smtp.mailfrom=axboe@kernel.dk X-HE-Tag: 1633468822-868695 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/5/21 3:18 PM, Andrew Morton wrote: > On Tue, 5 Oct 2021 09:31:43 -0600 Jens Axboe wrote: > >> Allocations can be a very hot path, and this out-of-line function >> call is noticeable. >> >> --- a/include/linux/fault-inject.h >> +++ b/include/linux/fault-inject.h >> @@ -64,8 +64,8 @@ static inline struct dentry *fault_create_debugfs_attr(const char *name, >> >> struct kmem_cache; >> >> -int should_failslab(struct kmem_cache *s, gfp_t gfpflags); >> #ifdef CONFIG_FAILSLAB >> +int should_failslab(struct kmem_cache *s, gfp_t gfpflags); >> extern bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags); >> #else >> static inline bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags) >> diff --git a/mm/slab.h b/mm/slab.h >> index 58c01a34e5b8..92fd6fe01877 100644 >> --- a/mm/slab.h >> +++ b/mm/slab.h >> @@ -491,8 +491,10 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, >> >> might_alloc(flags); >> >> +#ifdef CONFIG_FAILSLAB >> if (should_failslab(s, flags)) >> return NULL; >> +#endif > > Can we avoid the ifdefs here? > >> >> if (!memcg_slab_pre_alloc_hook(s, objcgp, size, flags)) >> return NULL; >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index ec2bb0beed75..c21bd447f237 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -1323,6 +1323,7 @@ EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); >> EXPORT_TRACEPOINT_SYMBOL(kfree); >> EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); >> >> +#ifdef CONFIG_FAILSLAB >> int should_failslab(struct kmem_cache *s, gfp_t gfpflags) >> { >> if (__should_failslab(s, gfpflags)) >> @@ -1330,3 +1331,4 @@ int should_failslab(struct kmem_cache *s, gfp_t gfpflags) >> return 0; >> } >> ALLOW_ERROR_INJECTION(should_failslab, ERRNO); >> +#endif > > Like, > > --- a/include/linux/fault-inject.h~mm-dont-call-should_failslab-for-config_failslab-fix > +++ a/include/linux/fault-inject.h > @@ -68,6 +68,10 @@ struct kmem_cache; > int should_failslab(struct kmem_cache *s, gfp_t gfpflags); > extern bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags); > #else > +static inline int should_failslab(struct kmem_cache *s, gfp_t gfpflags) > +{ > + return 0; > +} > static inline bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags) > { > return false; > --- a/mm/slab.h~mm-dont-call-should_failslab-for-config_failslab-fix > +++ a/mm/slab.h > @@ -491,10 +491,8 @@ static inline struct kmem_cache *slab_pr > > might_alloc(flags); > > -#ifdef CONFIG_FAILSLAB > if (should_failslab(s, flags)) > return NULL; > -#endif > > if (!memcg_slab_pre_alloc_hook(s, objcgp, size, flags)) > return NULL; > _ Yep, that'll work! -- Jens Axboe