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Received: from 30.120.38.205(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X4dcBhE_1781179868 cluster:ay36) by smtp.aliyun-inc.com; Thu, 11 Jun 2026 20:11:09 +0800 Message-ID: Date: Thu, 11 Jun 2026 20:11:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 04/11] mm: khugepaged: add shmem mTHP collapse support To: Lance Yang Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, hughd@google.com, willy@infradead.org, ziy@nvidia.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <3895c09794739bbfae99d9e021ffacf8a51fb8e2.1781083630.git.baolin.wang@linux.alibaba.com> <20260611060619.94738-1-lance.yang@linux.dev> From: Baolin Wang In-Reply-To: <20260611060619.94738-1-lance.yang@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1629012000E X-Stat-Signature: fsqwd5af5cekz66aei5yssmq7nzw1p45 X-Rspam-User: X-HE-Tag: 1781179875-750017 X-HE-Meta: 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 l/XahN4Z HR/hldhqqR6lEFJS9v32aP6pZDODCfWkSdYRBzbYtU1D1iqmXtz7/Pdz0kZg7T2DL2VvBNkx2zEi/JzDbgJ95TiZmejT7s2MkATYeQJk8/cYOMX07EmvSzGq70zqxPkWsXBhPnqLa5TMDoL5fn/hbRzdb+nxPoJ/SxYZ11Rx+9jBOPE1Tkkqj4MXDxURk8eewLfGYleU9c+CqakM6qgnjbRWjsiKp68givyYoIbVOZr4pdPUktJ1ymvBePb83K7gtVirKgDh8gVidNtZ/2zGTcq9lD0sBstVz50UxRQVVvu24rn5ZHN4c4lB8aS95NmM2lF3mFrt3hrpJLZEvAVtdwmS9dH9QYLjHGSZUfdXBEp3Pi5Y= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/11/26 2:06 PM, Lance Yang wrote: > > On Wed, Jun 10, 2026 at 06:29:12PM +0800, Baolin Wang wrote: > [...] >> @@ -2768,15 +2827,23 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, >> else >> cc->progress += HPAGE_PMD_NR; >> >> - if (result == SCAN_SUCCEED) { >> - if (present < HPAGE_PMD_NR - max_ptes_none) { >> - result = SCAN_EXCEED_NONE_PTE; >> - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); >> - } else { >> - result = collapse_file(mm, addr, file, start, cc, HPAGE_PMD_ORDER); >> - } >> + if (result != SCAN_SUCCEED) >> + goto out; >> + >> + if (present < HPAGE_PMD_NR - max_ptes_none) { >> + result = SCAN_EXCEED_NONE_PTE; >> + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); >> + count_mthp_stat(HPAGE_PMD_ORDER, >> + MTHP_STAT_COLLAPSE_EXCEED_NONE); >> + goto out; >> } >> >> + result = mthp_collapse(mm, file, start, addr, 0, 0, cc, enabled_orders); > > Feels like the second 0 wants to be "swap", no? It seems so. This reminds me of the issue you’re trying to fix in [1]. [1] https://lore.kernel.org/all/20260609120443.71864-1-lance.yang@linux.dev/