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Tue, 10 Dec 2024 09:48:15 +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 ytilJV8OWGdROAAAD6G6ig (envelope-from ); Tue, 10 Dec 2024 09:48:15 +0000 Message-ID: Date: Tue, 10 Dec 2024 10:48:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy() Content-Language: en-US To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Johannes Weiner , Zi Yan , Yu Zhao , stable@vger.kernel.org References: <20241210093437.174413-1-david@redhat.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: <20241210093437.174413-1-david@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: 347A1A001D X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: qqyeichtbs19kcm74igajbtpfzo434xh X-HE-Tag: 1733824074-78430 X-HE-Meta: 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 R8x8tXsD 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 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 12/10/24 10:34, David Hildenbrand wrote: > In split_large_buddy(), we might call pfn_to_page() on a PFN that might > not exist. In corner cases, such as when freeing the highest pageblock in > the last memory section, this could result with CONFIG_SPARSEMEM && > !CONFIG_SPARSEMEM_EXTREME in __pfn_to_section() returning NULL and > and __section_mem_map_addr() dereferencing that NULL pointer. > > Let's fix it, and avoid doing a pfn_to_page() call for the first > iteration, where we already have the page. > > So far this was found by code inspection, but let's just CC stable as > the fix is easy. > > Fixes: fd919a85cd55 ("mm: page_isolation: prepare for hygienic freelists") > Reported-by: Vlastimil Babka > Closes: https://lkml.kernel.org/r/e1a898ba-a717-4d20-9144-29df1a6c8813@suse.cz > Cc: Andrew Morton > Cc: Johannes Weiner > Cc: Zi Yan > Cc: Yu Zhao > Cc: > Signed-off-by: David Hildenbrand Reviewed-by: Vlastimil Babka Thanks! > --- > mm/page_alloc.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 48a291c485df4..a52c6022c65cb 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1238,13 +1238,15 @@ static void split_large_buddy(struct zone *zone, struct page *page, > if (order > pageblock_order) > order = pageblock_order; > > - while (pfn != end) { > + do { > int mt = get_pfnblock_migratetype(page, pfn); > > __free_one_page(page, pfn, zone, order, mt, fpi); > pfn += 1 << order; > + if (pfn == end) > + break; > page = pfn_to_page(pfn); > - } > + } while (1); > } > > static void free_one_page(struct zone *zone, struct page *page,