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Wed, 12 Mar 2025 15:28:27 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHZeM9wczXZsu7wvYHlQhoFZMC1P9eBQ6a7llT4AWbfvkX2V4gxTt/g0q4aWxVJQlCpMgPGEQ== X-Received: by 2002:a05:622a:2449:b0:476:75d0:a1d0 with SMTP id d75a77b69052e-47675d0a3b6mr297012831cf.1.1741818506831; Wed, 12 Mar 2025 15:28:26 -0700 (PDT) Received: from x1.local ([85.131.185.92]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-476bb66f9ccsm535261cf.47.2025.03.12.15.28.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Mar 2025 15:28:26 -0700 (PDT) Date: Wed, 12 Mar 2025 18:28:22 -0400 From: Peter Xu To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Mike Rapoport , Al Viro , Axel Rasmussen , Pavel Emelyanov , Jinjiang Tu , Dimitris Siakavaras , Andrea Arcangeli Subject: Re: [PATCH] mm/userfaultfd: Fix release hang over concurrent GUP Message-ID: References: <20250312145131.1143062-1-peterx@redhat.com> <20250312150411.f4a5b406600742a49b46d04e@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250312150411.f4a5b406600742a49b46d04e@linux-foundation.org> On Wed, Mar 12, 2025 at 03:04:11PM -0700, Andrew Morton wrote: > It would be good to have a Fixes: target but this bug seems to be so > old that a bare cc:stable should be OK? Yes I agree that should work for us, sorry I forgot to try attach that from time to time.. AFAIU, such unwanted behavior (either GUP hangs, or if before commit 656710a60e36, the behavior could be a SIGBUS returned to GUP racing with the userfaultfd_release()) should exist since the 1st day, but I didn't verify the original commit. Thanks, -- Peter Xu