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b=BsXgTAIkqJ4ZLkU5skRR/MDSORPF04knOdC/H4EZxMVI4JiV6nhSrssbbSFpwWEL60RrOF5j+tRW1MQ7nhbvABSxk3JXri4oENOqn4t9QHzavYNkSy/o/tD2Pm0YIACpVspBRuck4bQmzoydGCD7mBpc9ABeIE0ZWz4+t//sGOs= Received: from 30.74.146.9(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WYoKRf3_1746007953 cluster:ay36) by smtp.aliyun-inc.com; Wed, 30 Apr 2025 18:12:34 +0800 Message-ID: Date: Wed, 30 Apr 2025 18:12:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 09/12] khugepaged: avoid unnecessary mTHP collapse attempts To: Nico Pache , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, david@redhat.com, baohua@kernel.org, ryan.roberts@arm.com, willy@infradead.org, peterx@redhat.com, ziy@nvidia.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, dev.jain@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com References: <20250428181218.85925-1-npache@redhat.com> <20250428181218.85925-10-npache@redhat.com> From: Baolin Wang In-Reply-To: <20250428181218.85925-10-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 21D4DC0010 X-Stat-Signature: xgji34pyag7a5h8bqczctig945rkj3zz X-HE-Tag: 1746007959-672595 X-HE-Meta: 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 Gzn6Ie3i PBTa0awWvKQNhirEIxnCwTW0osWZq7CFdaOMxRrcoYT8tyHK1LKSLgZPRf22qZLkX9XrY6CROkL/hCdCNAOAi5rO533O9yRkD7YIG0APpGwdBodQEF1qHZQsn7yy7bRAEic1MjrZRr+gmECbNATIwTORDxqnnX3eomWsDoAYHk4vCea859tUEIjZ1Io5NeuycIo3GhJbGR3RzSJ6GyusvtIHnmCK6beD0r1Gyyf5j7aOwEkECBdJQytnP7yTdR9SGgAcGD40WSThwDky5p8gL9KWuoH50weDYwdFwGjHsZW7mjGkAU37CTsX0M5HVmu6rYVNI0i9gB5NW1SgPzTKO4bw0XBrW1DafUCv9 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/4/29 02:12, Nico Pache wrote: > There are cases where, if an attempted collapse fails, all subsequent > orders are guaranteed to also fail. Avoid these collapse attempts by > bailing out early. > > Signed-off-by: Nico Pache > --- > mm/khugepaged.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 86d1153ce9e8..5e6732cccb86 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1365,6 +1365,23 @@ static int khugepaged_scan_bitmap(struct mm_struct *mm, unsigned long address, > collapsed += (1 << order); > continue; > } > + /* > + * Some ret values indicate all lower order will also > + * fail, dont trying to collapse smaller orders > + */ > + if (ret == SCAN_EXCEED_NONE_PTE || > + ret == SCAN_EXCEED_SWAP_PTE || > + ret == SCAN_EXCEED_SHARED_PTE || > + ret == SCAN_PTE_NON_PRESENT || > + ret == SCAN_PTE_UFFD_WP || > + ret == SCAN_ALLOC_HUGE_PAGE_FAIL || > + ret == SCAN_CGROUP_CHARGE_FAIL || > + ret == SCAN_COPY_MC || > + ret == SCAN_PAGE_LOCK || > + ret == SCAN_PAGE_COUNT) > + goto next; > + else > + break; Better to merge this patch into patch 6, which can be helped to understand your logic.