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[109.81.31.109]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b70bedcec19sm413921266b.7.2025.11.03.10.22.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Nov 2025 10:22:10 -0800 (PST) Date: Mon, 3 Nov 2025 19:22:09 +0100 From: Michal Hocko To: Ankit Agrawal Cc: Andrew Morton , Aniket Agashe , Vikram Sethi , Jason Gunthorpe , Matt Ochs , Shameer Kolothum , "linmiaohe@huawei.com" , "nao.horiguchi@gmail.com" , "david@redhat.com" , "lorenzo.stoakes@oracle.com" , "Liam.Howlett@oracle.com" , "vbabka@suse.cz" , "rppt@kernel.org" , "surenb@google.com" , "tony.luck@intel.com" , "bp@alien8.de" , "rafael@kernel.org" , "guohanjun@huawei.com" , "mchehab@kernel.org" , "lenb@kernel.org" , "kevin.tian@intel.com" , "alex@shazbot.org" , Neo Jia , Kirti Wankhede , "Tarun Gupta (SW-GPU)" , Zhi Wang , Dheeraj Nigam , Krishnakant Jaju , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-edac@vger.kernel.org" , "Jonathan.Cameron@huawei.com" , "ira.weiny@intel.com" , "Smita.KoralahalliChannabasappa@amd.com" , "u.kleine-koenig@baylibre.com" , "peterz@infradead.org" , "linux-acpi@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v4 2/3] mm: handle poisoning of pfn without struct pages Message-ID: References: <20251026141919.2261-1-ankita@nvidia.com> <20251026141919.2261-3-ankita@nvidia.com> <20251027172620.d764b8e0eab34abd427d7945@linux-foundation.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sun 02-11-25 11:55:56, Ankit Agrawal wrote: > >> >> +static void add_to_kill_pfn(struct task_struct *tsk, > >> >> +                         struct vm_area_struct *vma, > >> >> +                         struct list_head *to_kill, > >> >> +                         unsigned long pfn) > >> >> +{ > >> >> +     struct to_kill *tk; > >> >> + > >> >> +     tk = kmalloc(sizeof(*tk), GFP_ATOMIC); > >> >> +     if (!tk) > >> >> +             return; > >> > > >> > This is unfortunate.  GFP_ATOMIC is unreliable and we silently behave > >> > as if it worked OK. > >> > >> Got it. I'll mark this as a failure case. > > > > why do you need to batch all processes and kill them at once? Can you > > just kill one by one? > > Hi Michal, I am trying to replicate what is being done today for non-PFNMAP > memory failure in __add_to_kill > (https://github.com/torvalds/linux/blob/master/mm/memory-failure.c#L376). > For this series, I am inclined to keep it uniform. Unless there is a very good reason for this code then I would rather not rely on an atomic allocation. This just makes the behavior hard to predict -- Michal Hocko SUSE Labs