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dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1739272526; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=20r1ifiVTnofGXAZmkg7JRpuBOwZYU47bd0iakC4IHQ=; b=q2ig+EaPoztsxrjS9IDcIfhjW+KaKo96llcbfgqUSBQVyjjeqHdmLZWZxS/oEaArXY2CFT fKjRflUsaNvp2PkX9yh+oHsgjf72Uk6P6P+bnc/twXPe4QOTZZX1KwXE0o6qVzE0uKuNtP j0w6ppOxzs1DZkbL7Klav2J4sxhPXzQ= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 11C3313D5; Tue, 11 Feb 2025 03:15:47 -0800 (PST) Received: from K4MQJ0H1H2.emea.arm.com (K4MQJ0H1H2.blr.arm.com [10.162.40.80]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D8CDC3F5A1; Tue, 11 Feb 2025 03:15:15 -0800 (PST) From: Dev Jain To: akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, kirill.shutemov@linux.intel.com Cc: npache@redhat.com, ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, srivatsa@csail.mit.edu, haowenchao22@gmail.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, jglisse@google.com, surenb@google.com, vishal.moola@gmail.com, zokeefe@google.com, zhengqi.arch@bytedance.com, jhubbard@nvidia.com, 21cnbao@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dev Jain Subject: [PATCH v2 10/17] khugepaged: Exit early on fully-mapped aligned mTHP Date: Tue, 11 Feb 2025 16:43:19 +0530 Message-Id: <20250211111326.14295-11-dev.jain@arm.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20250211111326.14295-1-dev.jain@arm.com> References: <20250211111326.14295-1-dev.jain@arm.com> MIME-Version: 1.0 X-Stat-Signature: kgr3qmjpdi3hgyoffju1ut6ro3hg3xn8 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 54D6D140011 X-Rspam-User: X-HE-Tag: 1739272526-77618 X-HE-Meta: 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 dPSSgVhp UXN70MTLRKnrTYRq7mPkbdC1UYyE8QGSM+PDxC+8/XSQHmoA2XNbwcj7yGytlrSg08+w/PwXLkwZTXK0lVtDajfZoz3vUyHptxH6nYkNk2ut4tDkE+WOhchpIJSpflbpTY9Uvyq9fS5+x+cNmdxZJagM+3lMP3HpJfLpuafky4Q5LWgJy6E0DvoHTzafgGvh5DdjifmoR+dXDaoEimXM/z0xwm2yDo6Ow95w6 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: Since mTHP orders under consideration by khugepaged are also candidates for the fault handler, the case we hit frequently is that khugepaged scans a region for order-x, whereas an order-x folio was already installed by the fault handler there. Therefore, exit early; this prevents a timeout in the khugepaged selftest. Earlier this was not a problem because a PMD-hugepage will get checked by find_pmd_or_thp_or_none(), and the previous patch does not solve this problem because it will do the entire PTE scan to exit. Signed-off-by: Dev Jain --- mm/khugepaged.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 0d0d8f415a2e..baa5b44968ac 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -626,6 +626,11 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); + if (_pte == pte && (order != HPAGE_PMD_ORDER) && (folio_order(folio) == order) && + test_bit(PG_head, &folio->page.flags) && !folio_test_partially_mapped(folio)) { + result = SCAN_PTE_MAPPED_THP; + goto out; + } /* See hpage_collapse_scan_pmd(). */ if (folio_likely_mapped_shared(folio)) { ++shared; @@ -1532,6 +1537,16 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, goto out_unmap; } + /* Exit early: There is high chance of this due to faulting */ + if (_pte == pte && (order != HPAGE_PMD_ORDER) && (folio_order(folio) == order) && + test_bit(PG_head, &folio->page.flags) && !folio_test_partially_mapped(folio)) { + pte_unmap_unlock(pte, ptl); + _address = address + (PAGE_SIZE << order); + _pte = pte + (1UL << order); + result = SCAN_PTE_MAPPED_THP; + goto decide_order; + } + /* * We treat a single page as shared if any part of the THP * is shared. "False negatives" from