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Wed, 29 Oct 2025 09:05:24 -0700 (PDT) Date: Wed, 29 Oct 2025 09:05:18 -0700 From: Isaac Manjarres To: David Hildenbrand Cc: Mike Rapoport , Andrew Morton , stable@vger.kernel.org, kernel-team@android.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] mm/mm_init: Fix hash table order logging in alloc_large_system_hash() Message-ID: References: <20251028191020.413002-1-isaacmanjarres@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Queue-Id: 6DFB940009 X-Rspamd-Server: rspam03 X-Stat-Signature: u9ttwjtuakwtfstaxphfcogez6mcffot X-HE-Tag: 1761753926-320276 X-HE-Meta: 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 bKqTfppe 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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 Wed, Oct 29, 2025 at 04:58:37PM +0100, David Hildenbrand wrote: > On 29.10.25 16:50, Isaac Manjarres wrote: > > On Wed, Oct 29, 2025 at 11:03:18AM +0100, David Hildenbrand wrote: > > > On 28.10.25 20:10, Isaac J. Manjarres wrote: > > > > When emitting the order of the allocation for a hash table, > > > > alloc_large_system_hash() unconditionally subtracts PAGE_SHIFT from > > > > log base 2 of the allocation size. This is not correct if the > > > > allocation size is smaller than a page, and yields a negative value > > > > for the order as seen below: > > > > > > > > TCP established hash table entries: 32 (order: -4, 256 bytes, linear) > > > > TCP bind hash table entries: 32 (order: -2, 1024 bytes, linear) > > > > > > > > Use get_order() to compute the order when emitting the hash table > > > > information to correctly handle cases where the allocation size is > > > > smaller than a page: > > > > > > > > TCP established hash table entries: 32 (order: 0, 256 bytes, linear) > > > > TCP bind hash table entries: 32 (order: 0, 1024 bytes, linear) > > > > > > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > > > > Cc: stable@vger.kernel.org # v5.4+ > > > > > > This is a pr_info(), why do you think this is stable material? Just curious, > > > intuitively I'd have said that it's not that critical. > > > > > > > Hi David, > > > > Thank you for taking the time to review this patch! I was just under the > > impression that any bug--even those for informational logging--should be > > sent to stable as well. > > See https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html > > In particular: > > " > It fixes a problem like an oops, a hang, data corruption, a real security > issue, a hardware quirk, a build error (but not for things marked > CONFIG_BROKEN), or some “oh, that’s not good” issue. > > Serious issues as reported by a user of a distribution kernel may also be > considered if they fix a notable performance or interactivity issue. ... > " > > -- > Cheers > > David / dhildenb > Thank you for pointing that out, sorry about that. I'll keep that in mind moving forward. Thanks, Isaac