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b=n03tXMcpjjYNt0Hx9YQwbPGwEDXWZKfUKohUo5ohPUHbPx+f8qh+KDZeTzpBbg3/7 LokGmm0Pw75YvFbCHRFosn/8qYVSWw0qa92DFLMAQG6xmDRvM6NK+zWmACR7qoWvYF QyWcblJX4j+wv1GSRREER4cGbV/YrZaU//IBoy1I= Date: Fri, 27 Mar 2026 09:47:38 -0700 From: Andrew Morton To: Suren Baghdasaryan Cc: willy@infradead.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, lorenzo.stoakes@oracle.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 Subject: Re: [PATCH v5 0/6] Use killable vma write locking in most places Message-Id: <20260327094738.7150efc3b0619e6ccf095c23@linux-foundation.org> In-Reply-To: <20260326080836.695207-1-surenb@google.com> References: <20260326080836.695207-1-surenb@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 965D8160008 X-Stat-Signature: opb1gntzchot5dqx3ueqh4effe1d7hdk X-Rspamd-Server: rspam06 X-HE-Tag: 1774630061-898710 X-HE-Meta: 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 PYMxx0Yw K6EUVAwUS7dQKLq+rRXp0FN1M78tLdvTy/eAtjQB68Pp1nQYLVxKeQ9OGQM/EjK4Tg19/nWb+mSZcF9UdlLhyZJIQv3nSCkdXtDIzIF1DEX9ThT6IRF34+Lsvlgkp/RbrIwzMY2pZziobCK04hECA6yZDiQRuyqBAaOnre7Yj18/933OOu9mgNvKC1SsV7kVTdq7uXedRWwvRy6IFuQqIbTxIDhaWS9lolhuQw/l2ByEYXyOhXotpk1rNFVPWXdXmsEnnlO1nrfu7PpCJa0AH7hznd+4+/h5+OTgTUgAoBCC+fdmBGbw1FM/WpS3tYOalndJj9omRUgp8tFFVg5TPg8V1UzJlYhmDeHAu Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 26 Mar 2026 01:08:30 -0700 Suren Baghdasaryan wrote: > Now that we have vma_start_write_killable() we can replace most of the > vma_start_write() calls with it, improving reaction time to the kill > signal. > > There are several places which are left untouched by this patchset: > > 1. free_pgtables() because function should free page tables even if a > fatal signal is pending. > > 2. userfaultd code, where some paths calling vma_start_write() can > handle EINTR and some can't without a deeper code refactoring. > > 3. mpol_rebind_mm() which is used by cpusset controller for migrations > and operates on a remote mm. Incomplete operations here would result > in an inconsistent cgroup state. > > 4. vm_flags_{set|mod|clear} require refactoring that involves moving > vma_start_write() out of these functions and replacing it with > vma_assert_write_locked(), then callers of these functions should > lock the vma themselves using vma_start_write_killable() whenever > possible. Thanks, I added this to mm-new. It doesn't appear to fix anything and it has no appreciable&measured performance benefits, so I just broke my own rule. Weasel words: Lorenzo would like it in 7.0, unreviewed patches in mm-unstable&mm-new are down to 62 and I'm a sucker for nice patchsets. Three of your patches lack review tags so now it's 65!