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Received: from 30.74.144.121(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X-rk77J_1773390827 cluster:ay36) by smtp.aliyun-inc.com; Fri, 13 Mar 2026 16:33:48 +0800 Message-ID: Date: Fri, 13 Mar 2026 16:33:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-unstable v3 5/5] mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() To: Nico Pache , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jackmanb@google.com, jack@suse.cz, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com References: <20260311211315.450947-1-npache@redhat.com> <20260311211315.450947-6-npache@redhat.com> From: Baolin Wang In-Reply-To: <20260311211315.450947-6-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: roq6fc3rquzcenmhcb7jj77yhqw8z9id X-Rspamd-Queue-Id: E9C7940007 X-Rspamd-Server: rspam03 X-HE-Tag: 1773390834-272448 X-HE-Meta: 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 /FqjGwkc zXm4Vq7cB4wSZUBUgBLcK1pw31qFaju7AmQicw2fKox0vURE494nantPrWVdCrVOGt/3fuzES0tS7/cdjqG+CSXd/6YReOFlrIx1fl0n0DhRLo1xBjIRGAhmqBrih2lal+FDP3unRLXvsuly6x1pw+i/icoLwmAz30AfOHcgP5g1IsEI0d0bGtKAjeLCJ5kqANIezy8soPoMy9JzSp7z5qHx9RTUT/s2FWoZvd7+AmUGm1V1lj0LTphxdFZ2etYRXWgGfvJGpkSqHdVM2anAtJeMSCxAAM0kDxbHuos/BUEJi/pBOJ/0UHyV6/KBaTIFLnIYPv6rcGCAYvuyGvqsADzXsQA1/i0K3CPh3vHQ4nYkCwIH+QOEUzKfzc5cbKAGyNjDZtKnlx1zVWwOMoesBPoGgJNRLA6mI3gYJh/vI/7QbwuGCdbm5iIWUgIPcf390xnIw Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/12/26 5:13 AM, Nico Pache wrote: > The khugepaged daemon and madvise_collapse have two different > implementations that do almost the same thing. Create collapse_single_pmd > to increase code reuse and create an entry point to these two users. > > Refactor madvise_collapse and collapse_scan_mm_slot to use the new > collapse_single_pmd function. This introduces a minor behavioral change > that is most likely an undiscovered bug. The current implementation of > khugepaged tests collapse_test_exit_or_disable before calling > collapse_pte_mapped_thp, but we weren't doing it in the madvise_collapse > case. By unifying these two callers madvise_collapse now also performs > this check. We also modify the return value to be SCAN_ANY_PROCESS which > properly indicates that this process is no longer valid to operate on. > > By moving the madvise_collapse writeback-retry logic into the helper > function we can also avoid having to revalidate the VMA. > > We also guard the khugepaged_pages_collapsed variable to ensure its only > incremented for khugepaged. > > Signed-off-by: Nico Pache > --- LGTM. Reviewed-by: Baolin Wang