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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxcqD-0000000Cdoe-3gHX; Wed, 04 Mar 2026 03:24:05 +0000 Date: Wed, 4 Mar 2026 03:24:05 +0000 From: Matthew Wilcox To: Suren Baghdasaryan Cc: Lorenzo Stoakes , akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, vbabka@suse.cz, jannh@google.com, rppt@kernel.org, mhocko@suse.com, pfalcato@suse.de, kees@kernel.org, maddy@linux.ibm.com, npiggin@gmail.com, mpe@ellerman.id.au, chleroy@kernel.org, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, gerald.schaefer@linux.ibm.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, "Ritesh Harjani (IBM)" Subject: Re: [PATCH v3 2/3] mm: replace vma_start_write() with vma_start_write_killable() Message-ID: References: <20260226070609.3072570-1-surenb@google.com> <20260226070609.3072570-3-surenb@google.com> <74bffc7a-2b8c-40ae-ab02-cd0ced082e18@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 9225610000E X-Stat-Signature: yc3u4ajyu1pnpf4qmh1cgbdn4uohguaj X-Rspam-User: X-HE-Tag: 1772594667-549994 X-HE-Meta: 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 bL06lfdz GoqI1wWOPZrv+LIJ2+s9QIX/hMeAkFMij7RDkOtyhZEd2I4ZiUqaY8ZdgYaTzOm9A3WZzjZoYtl2lJAk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 03, 2026 at 04:02:50PM -0800, Suren Baghdasaryan wrote: > On Tue, Mar 3, 2026 at 2:18 PM Matthew Wilcox wrote: > > > > On Tue, Mar 03, 2026 at 02:11:31PM -0800, Suren Baghdasaryan wrote: > > > On Mon, Mar 2, 2026 at 6:53 AM Lorenzo Stoakes > > > wrote: > > > > Overall I'm a little concerned about whether callers can handle -EINTR in all > > > > cases, have you checked? Might we cause some weirdness in userspace if a syscall > > > > suddenly returns -EINTR when before it didn't? > > > > > > I did check the kernel users and put the patchset through AI reviews. > > > I haven't checked if any of the affected syscalls do not advertise > > > -EINTR as a possible error. Adding that to my todo list for the next > > > respin. > > > > This only allows interruption by *fatal* signals. ie there's no way > > that userspace will see -EINTR because it's dead before the syscall > > returns to userspace. That was the whole point of killable instead of > > interruptible. > > Ah, I see. So, IIUC, that means any syscall can potentially fail with > -EINTR and this failure code doesn't need to be documented. Is that > right? We could literally return any error code -- it never makes it to userspace. I forget where it is, but if you follow the syscall return to user path, a dying task never makes it to running a single instruction.