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[67.164.59.41]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-24ca63c9e71sm18196285ad.95.2025.09.03.11.13.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Sep 2025 11:13:03 -0700 (PDT) Date: Wed, 3 Sep 2025 11:12:59 -0700 From: "Vishal Moola (Oracle)" To: David Hildenbrand Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Kees Cook , kernel test robot , Dan Carpenter Subject: Re: [PATCH] mm: Fix kernel stack tagging for certain configs Message-ID: References: <20250902175903.1124555-1-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: ECFA5180010 X-Stat-Signature: 67cx1kg5gtbp5mnpuyp1rkiuzy8i1tg6 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1756923185-22466 X-HE-Meta: U2FsdGVkX181zrfaEfTCVoHMMIqk83w0UgUZeqVz18EuAM8zQHHe2zZAZvlpGKO+6LygaBJp7oxgfAe3VDydrbuRAc33X2n8D44pWrWWaXyliuKCA9Ln2Euvr/Z3tNW3+9mOem0zLedWK2MlSFPIq7KYTb6s+JyO7ylKqtjYfnCCx4WPivTyk/Va2ve+a0udfOHjcc7ExGDLrcFVm4PrBrYZ68N+F8Zgbg8u7HxRGEk9MKL/RJ7PkU7mOuH57xfWsFGbxIO5fVhO5m8y5+YOSp7NjH2JG6sHCAja0r2pPqfMts3g+suS+710RnwlrwVjkf9svNkcV/ZeeqcEKlHRG9dgHgCpYE/97Iyej7dSskbM9VLQpd9oO5M78kn8E/gqmFmqyyDqL2ECSGjj/AYQO6aWbcipwxFWRc9vA6JgbscBsah26i7TcbSY+ZKYCs6Be6oClPjDDBCYRKPmbwtZfMAjqVQLZcS6SWO01PWr1tDYTlZ0Wnd14ffijKI2g38IbqGb/sL0SxaP2DfoAM72v77hUrivEGQ86qiZh1y3nKqg0CKVm0u7gJ0GpRDTXUQW2y/yzfCcvJGw4ZH4hUqclRVyGCoO04u5yGFs/jgw6ax1szKsF+JEB3fmA4DxWHScAVXlwpg5RReZnnZs5wQwHTnXERfr6TqafUlAQc6ZNCOXlrsHafkjppyNJC2UhItT6LA2FufU8BMki7ixk8N3mVu5/jSHIm8fDmwAhWhPk2+w3sQmWXJWL5Mo5XGS2JTQOn7bycvBm30GIC6lHxJwKusEv2EagXm6mil2qaQ0CqO2U/SDm4lT/8sNO1PnYjhPYZEweaavnPpFaKdIPC98iJ71cTreSEGA/lQ3yjnZmAKagFUlqUo6NoQiEXefuKlFbVUuAke8LYWlzn2nHjCwqJU+e+Vd60ss4uJxrXVJMuOB6soIPLuM2t8e7MlzLr5rn1OhjsELwV13gkkvw/k xa+9SXMK 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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, Sep 03, 2025 at 09:46:44AM +0200, David Hildenbrand wrote: > On 02.09.25 22:06, Vishal Moola (Oracle) wrote: > > On Tue, Sep 02, 2025 at 08:23:06PM +0200, David Hildenbrand wrote: > > > On 02.09.25 19:59, Vishal Moola (Oracle) wrote: > > > > Commit 4ef905bda61f ("mm: tag kernel stack pages") began marking pages > > > > that were being used for the kernel stack. > > > > > > > > There are 3 cases where kernel pages are allocated for kernel stacks: > > > > CONFIG_VMAP_STACK, THREAD_SIZE >= PAGE_SIZE, THREAD_SIZE < PAGE_SIZE. > > > > These cases use vmalloc(), alloc_pages() and kmem_cache_alloc() > > > > respectively. > > > > > > > > In the first 2 cases, THREAD_SIZE / PAGE_SIZE will always be greater > > > > than 0, and pages are tagged as expected. In the third case, > > > > THREAD_SIZE / PAGE_SIZE evaluates to 0 and doesn't tag any pages at all. > > > > This meant that in those configs, the stack tagging was a no-op, and led > > > > to smatch build warnings. > > > > > > > > We definitely have at least 1 page we want tagged at this point, so fix > > > > it by using a do {} while loop instead of a for loop. > > > > > > > > Fixes: 4ef905bda61f ("mm: tag kernel stack pages") > > > > Reported-by: kernel test robot > > > > Reported-by: Dan Carpenter > > > > Closes: https://lore.kernel.org/r/202508300929.TrRovUMu-lkp@intel.com/ > > > > Signed-off-by: Vishal Moola (Oracle) > > > > --- > > > > > > You sent the patch on August 20 and I replied on August 21. > > > > > > I did not receive any reply so far. > > > > Ah sorry, I didn't mean to miss your reply. > > > > I can't find your reply in my inboxes so I definitely missed it somehow. > > I'll go find it and respond. > > I had a mail server config issue on one day last month (sending @redhat.com > through kernel.org :) ), let me check if that was on that problematic day > and it might have went straight into your spam folder due to dkim mismatch. > > So the mailing list did not reject it: > > https://lore.kernel.org/all/96148baf-f008-449b-988b-ea4f07d18528@redhat.com/ > > And yes, indeed, it was on that problemtic day, and there is: > > Received: from smtp.kernel.org > > So, problem on my side. Willy already replied, but let me resend that mail. > > > > > > And now I realize that this patch is not upstream yet and the commit id not > > > stable. So the Fixes/Closes etc. do not really apply. > > > > Gotcha. > > If there are bigger changes it usually makes sense to send a v2, or a simple > fixup as reply to the original patch (I prefer as inline reply). Ok I'll keep that in mind for the future :). My mail client loves attaching the fixup patches as additional files, but I'll find a workflow for inlining them. > Of course, once it's in mm-stable or upstream, things get more tricky :) > > -- > Cheers > > David / dhildenb >