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b=xsXDTggG3THVc8alSA3iSzbfXGCxq4u6omP46g/bxSKe75gXJwK6mXyvRDUoQ55eh3mpYiA2ItwK7VQ+/U+6gQMztIrLmGQkSASQrn1MXcBQLlUELb7lLRsnr8Z/LM8a8XA1w+D87aSyg2caV15G+G9TWRF0cZyov+hW6729geU= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R901e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033032089153;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=26;SR=0;TI=SMTPD_---0XAhNhUn_1789038410; Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XAhNhUn_1789038410 cluster:ay36) by smtp.aliyun-inc.com; Thu, 10 Sep 2026 19:06:51 +0800 Message-ID: Date: Thu, 10 Sep 2026 19:06:49 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 06/19] selftests/mm: stop khugepaged during the MADV_COLLAPSE cases To: Kiryl Shutsemau Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, rppt@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, usama.anjum@arm.com, usama.arif@linux.dev, nico.pache@linux.dev, ziy@nvidia.com, baohua@kernel.org, dev.jain@arm.com, hughd@google.com, lance.yang@linux.dev, liam@infradead.org, mhocko@suse.com, ryan.roberts@arm.com, shuah@kernel.org, surenb@google.com, vbabka@kernel.org, agordeev@linux.ibm.com, jgg@ziepe.ca, leon@kernel.org, kernel-team@meta.com References: <20260908125105.1510704-1-kirill@shutemov.name> <20260908125105.1510704-7-kirill@shutemov.name> <4e064b9d-aea9-485a-8547-3830999cff01@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D2E73100002 X-Stat-Signature: a7p86nt7g4ppkaajc4okuosdrag7eqmc X-HE-Tag: 1789038414-371904 X-HE-Meta: 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 HD+egds3 M3ueFWfz0K0mI0mW5vLj01pYYKodASNs6v1PI5HEZQHaBtYDOdQsMq/1Wfhbvv07KAMwwe/NOSVt7ynoNKciE8wfsAEqJ76DUJTcgEqKOBrRzRVYv2q1fqTdgedM1Uesd7vsO67YgSoNlqrP6PoHkxVWoCQ1jDLXWvhkAZQ79khxh/kYQsBELF9iwOVPQvJFGJ4r7CHTxc3mKB/h5s5Dw9AZfj6i/mDWkzJ+ZAFN4kDVUXJ2LFJY99RKwfQeKXKULmMHT2LgoN8nV+pS513bbD8C+OI5ZudfUZo7UJkqVpFZrj8zcQubM5bwq+yMoAf8pjAlCcvooMk+EV+oWGRdlrEVZ6D5B2rKfdetNrf1zQjR9b8P4B/yBGpItL5F/A4xgMdLd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/10/26 6:59 PM, Kiryl Shutsemau wrote: > On Thu, Sep 10, 2026 at 02:27:28PM +0800, Baolin Wang wrote: >> >> >> On 9/9/26 6:41 PM, Kiryl Shutsemau wrote: >>> On Wed, Sep 09, 2026 at 05:55:01PM +0800, Baolin Wang wrote: >>>> >>>> >>>> On 9/8/26 8:50 PM, Kiryl Shutsemau wrote: >>>>> From: "Kiryl Shutsemau (Meta)" >>>>> >>>>> __madvise_collapse() turns THP off before each MADV_COLLAPSE, both to keep >>>>> khugepaged out of the range and to prove MADV_COLLAPSE ignores the setting. >>>>> It clears the global controls only, which is no longer enough. A per-order >>>>> control overrides them, and -s, which makes the cases fault in folios of >>>>> one order, leaves that order's control at "always". khugepaged then >>>>> collapses the very range the case is working on, and the case fails on a >>>>> collapse that was interfered with rather than refused. >>>> >>>> Right. So I think the correct fix tag is b7f16963efe7 ("mm/khugepaged: run >>>> khugepaged for all orders"), because before this commit, khugepaged would >>>> not try to collapse this range since it only checked whether the PMD order >>>> was suitable for collapse. >>> >>> Agreed. The series is in mm-new already; if a respin is needed I will use >>> that tag. >>> >>>>> @@ -547,9 +547,16 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages, >>>>> /* >>>>> * Prevent khugepaged interference and tests that MADV_COLLAPSE >>>>> * ignores /sys/kernel/mm/transparent_hugepage/enabled >>>>> + * >>>>> + * "inherit" rather than "never" so that MADV_COLLAPSE on shmem still >>>>> + * finds an order to build. >>>>> */ >>>>> settings.thp_enabled = THP_NEVER; >>>>> settings.shmem_enabled = SHMEM_NEVER; >>>>> + for (i = 0; i < NR_ORDERS; i++) { >>>>> + settings.hugepages[i].enabled = THP_INHERIT; >>>>> + settings.shmem_hugepages[i].enabled = SHMEM_INHERIT; >>>>> + } >>>> >>>> This looks like a workaround to me. Shouldn't we fix this in shmem instead? >>> >>> Good point. >>> >>> It can be a follow-up patch. Do you want to make a proper shmem.c fix >>> and update the selftest along with it? >> >> Either way works for me. > > Please, do it as a standlone shmem fix, plus selftest update to reflect > the change. Ah, sorry, I misunderstood your points. I'll send out a fix patch tomorrow.