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Fri, 3 Nov 2023 15:30:02 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Dv9JE/oRRWU8LwAAMHmgww (envelope-from ); Fri, 03 Nov 2023 15:30:02 +0000 Message-ID: <30ff0335-3d9c-7d54-85d0-5898320f4e1f@suse.cz> Date: Fri, 3 Nov 2023 16:30:01 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v2] efi/unaccepted: Fix off-by-one when checking for overlapping ranges Content-Language: en-US To: Michael Roth , linux-efi@vger.kernel.org Cc: x86@kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , "Kirill A . Shutemov" , Nikolay Borisov , stable@kernel.org, Tom Lendacky , Paolo Bonzini References: <20231103151354.110636-1-michael.roth@amd.com> From: Vlastimil Babka In-Reply-To: <20231103151354.110636-1-michael.roth@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 540C8C001C X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 97jmcfw8tjcdnh3pzpwdksrjmx9mqfk7 X-HE-Tag: 1699025404-788680 X-HE-Meta: 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 NUiLVLHE 59gSvj6ZPV//4tO7ooFd+1RfMDf4CsVHcq7i6ERYKKL4mywt36LG1SIi4PgUxaGc+h2ftTbbTooFOhY8h3t3R5yBg43g3676o++xQwLu4u5pdJDcaDc/kKYVGmGAeGZ6zxK6XJmC8PJiG7teBU494DmwHlvSWGX4pB1XIUXQNFkAg1ei2SUX0uymtXklMEQ1+s27ew3tF1sNAKgLzc4ECYiFLzKwfGkWvQePi+B5CrW4r45cHuICockQz41RgxHFSD4x4AeZZibNDfe3Co/gWFgdvSqG3zPIzmEnzlBa4Jf3r9e1o5j6P4lMMmS1UozolnViW95Hg5Fl1PW89LfgU/Tt+Pc3H7H3BmvNM 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 11/3/23 16:13, Michael Roth wrote: > When a task needs to accept memory it will scan the accepting_list > to see if any ranges already being processed by other tasks overlap > with its range. Due to an off-by-one in the range comparisons, a task > might falsely determine that an overlapping range is being accepted, > leading to an unnecessary delay before it begins processing the range. > > Fix the off-by-one in the range comparison to prevent this and slightly > improve performance. > > Fixes: 50e782a86c98 ("efi/unaccepted: Fix soft lockups caused by parallel memory acceptance") > Link: https://lore.kernel.org/linux-mm/20231101004523.vseyi5bezgfaht5i@amd.com/T/#me2eceb9906fcae5fe958b3fe88e41f920f8335b6 > Reviewed-by: Kirill A. Shutemov > Signed-off-by: Michael Roth More justification for introducing a common ranges_overlap() helper somewhere :) Acked-by: Vlastimil Babka > --- > v2: > * Improve commit message terminology (Kirill) > --- > drivers/firmware/efi/unaccepted_memory.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c > index 135278ddaf62..79fb687bb90f 100644 > --- a/drivers/firmware/efi/unaccepted_memory.c > +++ b/drivers/firmware/efi/unaccepted_memory.c > @@ -100,7 +100,7 @@ void accept_memory(phys_addr_t start, phys_addr_t end) > * overlap on physical address level. > */ > list_for_each_entry(entry, &accepting_list, list) { > - if (entry->end < range.start) > + if (entry->end <= range.start) > continue; > if (entry->start >= range.end) > continue;