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b=p8cv67e9ssUeWrFJGzAnKEG//LYmeqoUbvIrlKriZR7tjoP6HIKPNDX8pAccTwBH3 kXINSbiaDo1xDJrz/JeaCLaBaVqAnxS7nhEA2lvzOiuDnxxjG11JLenaxDm+s3Lxj2 gBLGMkVgja0Q4hASgoNQuIwIlGSxpW6FrxNNdPNh4/g6M+m2IOlHz4cIUNw50qQg28 S1E1hSZaFUqKAdRvL5ekKo6FKeATDlnWWE64vY5pnnLHk4JSh7QwNEnHPKQCu7T+j6 PIJ1RxF0irx8ZP6DGic6mucNZ5qkVhr+BkuZBSZI1pTlvap4lmikyHjbTLgwLSHuAZ l9ami0VnilBOQ== Date: Wed, 4 Mar 2026 16:53:27 +0000 From: "Lorenzo Stoakes (Oracle)" To: Matthew Wilcox Cc: Suren Baghdasaryan , 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: <76aff8f9-1c08-449a-a034-f3b93440d1a8@lucifer.local> 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-Queue-Id: DEBD320016 X-Stat-Signature: inyxrrdsebgbcga7zq351jr19jsm7j3g X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1772643211-884976 X-HE-Meta: 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 0PgvBr9G AyZVLSC6RWubV/H5LulXTSU5+kSwr4qiWkMcPHtRo16wX+VJ7+OaJ+dgeCkWAk15jnpIXA3Lw77IhYCLLtIv28hij3asqAemv+pKEOsdwuNf+s8Umtrj+n+rOWnopCramO8gzaEohpvKYka8H/RBxTr4xTO0p4bmVeUuhE/QxjvpqtQv4ATuAmt3k42gZUJKG96emYRId2BjiSOKc0PDFzVAVWUpYBeaFV/jHvrugq98CwliDteFBts5R4Tb6dBXZYvpUwjWrndw08a3qThSl12Rer5PBcTIFqP548/d0Q74Aud2GW9HAptC7Jt6oEAX9jVxhd/FTQVeTScNFQs1Z78mxqw9Iw1v4JNqNJEHJUskqRBfbkUy4Fxerk5P7rvlOnuxYNjvrnj8butsP2/GeYIbCG0Vnr+FYenjUeP14vrwtAI3XxuYyCZ5Y8BREBZ3YydmY Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 04, 2026 at 03:24:05AM +0000, Matthew Wilcox wrote: > 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. Thanks for that Matthew, that makes life easier then. We can probably replace some of the more horrid if (err == -EINTR) stuff with fatal_signal_pending(current) to be clearer as a result. Cheers, Lorenzo