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Tue, 25 Jun 2024 14:24:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id QJVZJjDTemaMKwAAD6G6ig (envelope-from ); Tue, 25 Jun 2024 14:24:48 +0000 Message-ID: <78177ff2-e140-4e81-9b2a-be5bece34cfc@suse.cz> Date: Tue, 25 Jun 2024 16:24:48 +0200 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/7] mm, slab: add static key for should_failslab() Content-Language: en-US To: Akinobu Mita , Christoph Lameter , David Rientjes , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Masami Hiramatsu , Steven Rostedt , Mark Rutland Cc: Jiri Olsa , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org References: <20240620-fault-injection-statickeys-v2-0-e23947d3d84b@suse.cz> <20240620-fault-injection-statickeys-v2-6-e23947d3d84b@suse.cz> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240620-fault-injection-statickeys-v2-6-e23947d3d84b@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Score: -2.79 X-Spam-Level: X-Spam-Flag: NO X-Spamd-Result: default: False [-2.79 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; FREEMAIL_TO(0.00)[gmail.com,linux.com,google.com,kernel.org,iogearbox.net,linux.ibm.com,intel.com,davemloft.net,goodmis.org,arm.com]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCPT_COUNT_TWELVE(0.00)[19]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; FREEMAIL_CC(0.00)[kernel.org,linux.dev,gmail.com,vger.kernel.org,kvack.org]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TAGGED_RCPT(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] On 6/20/24 12:49 AM, Vlastimil Babka wrote: > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3874,13 +3874,37 @@ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s, > 0, sizeof(void *)); > } > > -noinline int should_failslab(struct kmem_cache *s, gfp_t gfpflags) > +#if defined(CONFIG_FUNCTION_ERROR_INJECTION) || defined(CONFIG_FAILSLAB) > +DEFINE_STATIC_KEY_FALSE(should_failslab_active); > + > +#ifdef CONFIG_FUNCTION_ERROR_INJECTION > +noinline > +#else > +static inline > +#endif > +int should_failslab(struct kmem_cache *s, gfp_t gfpflags) Note that it has been found that (regardless of this series) gcc may clone this to a should_failslab.constprop.0 in case the function is empty because __should_failslab is compiled out (CONFIG_FAILSLAB=n). The "noinline" doesn't help - the original function stays but only the clone is actually being called, thus overriding the original function achieves nothing, see: https://github.com/bpftrace/bpftrace/issues/3258 So we could use __noclone to prevent that, and I was thinking by adding something this to error-injection.h: #ifdef CONFIG_FUNCTION_ERROR_INJECTION #define __error_injectable(alternative) noinline __noclone #else #define __error_injectable(alternative) alternative #endif and the usage here would be: __error_injectable(static inline) int should_failslab(...) Does that look acceptable, or is it too confusing that "static inline" is specified there as the storage class to use when error injection is actually disabled? > { > if (__should_failslab(s, gfpflags)) > return -ENOMEM; > return 0; > } > -ALLOW_ERROR_INJECTION(should_failslab, ERRNO); > +ALLOW_ERROR_INJECTION_KEY(should_failslab, ERRNO, &should_failslab_active); > + > +static __always_inline int should_failslab_wrapped(struct kmem_cache *s, > + gfp_t gfp) > +{ > + if (static_branch_unlikely(&should_failslab_active)) > + return should_failslab(s, gfp); > + else > + return 0; > +} > +#else > +static __always_inline int should_failslab_wrapped(struct kmem_cache *s, > + gfp_t gfp) > +{ > + return false; > +} > +#endif > > static __fastpath_inline > struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags) > @@ -3889,7 +3913,7 @@ struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags) > > might_alloc(flags); > > - if (unlikely(should_failslab(s, flags))) > + if (should_failslab_wrapped(s, flags)) > return NULL; > > return s; >