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Mon, 3 Jun 2024 09:31:32 +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 vvITD3SNXWbNAwAAD6G6ig (envelope-from ); Mon, 03 Jun 2024 09:31:32 +0000 Message-ID: Date: Mon, 3 Jun 2024 11:31:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] lib/alloc_tag: fix RCU imbalance in pgalloc_tag_get() Content-Language: en-US To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: kent.overstreet@linux.dev, pasha.tatashin@soleen.com, keescook@chromium.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel test robot References: <20240601233840.617458-1-surenb@google.com> 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: <20240601233840.617458-1-surenb@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D6EC3180002 X-Stat-Signature: zx75o1e786fxs1hj1xksezhwatgkh1qq X-HE-Tag: 1717407093-824785 X-HE-Meta: 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 3aMbY2lz H/GMZpj3Ql7tALY3aozIClKJZdp7/3nG+EOQ8T3hFTgVPxc8Ap0kqvm+OQpxVyaR9TSeyrRcaBpCA0xIvL9pB9bJuRwgi8MSLmzs5Ce1cDohGlDi7gCku/QeAIvSvg+Bz7lEcHspJiePPoPOKXkm3y2PL3ovKwQ/wDfhsYfU7nW2mmEGCrJyft6A/m4qcXfyaKcFxviN7qN/5MqbQuzCtrBk4ppCVWFczqLDunAK1tQX/kyQuiKb5+3HF4I78nYQmhQvkvdwf6zSSqCWMjGzs/R91BRK0dWB9hmzoVtmH03heRn4+j76r57TAeCyVqr/RodjEGuDqktq9Drstdvsh6L2lhIRwGAtfos55stZa8nsfnWDRbRAzfi1FTDsehEF9WI6fM0EmB68Ik/zmrvWxFN3UBQfD30oj8ibp 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: List-Subscribe: List-Unsubscribe: On 6/2/24 1:38 AM, Suren Baghdasaryan wrote: > put_page_tag_ref() should be called only when get_page_tag_ref() returns > a valid reference because only in that case get_page_tag_ref() enters RCU > read section while put_page_tag_ref() will call rcu_read_unlock() even if > the provided reference is NULL. Fix pgalloc_tag_get() which does not > follow this rule causing RCU imbalance. Add a warning in put_page_tag_ref() > to catch any future mistakes. > > Fixes: cc92eba1c88b ("mm: fix non-compound multi-order memory accounting in __free_pages") > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-lkp/202405271029.6d2f9c4c-lkp@intel.com > Signed-off-by: Suren Baghdasaryan > Cc: Kent Overstreet Acked-by: Vlastimil Babka > --- > include/linux/pgalloc_tag.h | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h > index 86ba5d33e43b..9cacadbd61f8 100644 > --- a/include/linux/pgalloc_tag.h > +++ b/include/linux/pgalloc_tag.h > @@ -37,6 +37,9 @@ static inline union codetag_ref *get_page_tag_ref(struct page *page) > > static inline void put_page_tag_ref(union codetag_ref *ref) > { > + if (WARN_ON(!ref)) > + return; > + > page_ext_put(page_ext_from_codetag_ref(ref)); > } > > @@ -102,9 +105,11 @@ static inline struct alloc_tag *pgalloc_tag_get(struct page *page) > union codetag_ref *ref = get_page_tag_ref(page); > > alloc_tag_sub_check(ref); > - if (ref && ref->ct) > - tag = ct_to_alloc_tag(ref->ct); > - put_page_tag_ref(ref); > + if (ref) { > + if (ref->ct) > + tag = ct_to_alloc_tag(ref->ct); > + put_page_tag_ref(ref); > + } > } > > return tag; > > base-commit: 065d3634d60843b8e338d405b844cc7f2e5e1c66