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Wed, 02 Jul 2025 02:00:36 -0400 X-MC-Unique: paYXR1uOMJuRxkW0FtiDog-1 X-Mimecast-MFC-AGG-ID: paYXR1uOMJuRxkW0FtiDog_1751436032 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3099A1953941; Wed, 2 Jul 2025 06:00:32 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.88.112]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E860F18003FC; Wed, 2 Jul 2025 06:00:16 +0000 (UTC) From: Nico Pache To: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.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, 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 Subject: [PATCH v8 08/15] khugepaged: skip collapsing mTHP to smaller orders Date: Tue, 1 Jul 2025 23:57:35 -0600 Message-ID: <20250702055742.102808-9-npache@redhat.com> In-Reply-To: <20250702055742.102808-1-npache@redhat.com> References: <20250702055742.102808-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 3E1A316000D X-Stat-Signature: 1e6obakmitmkyw175xn4agu17xetefp8 X-HE-Tag: 1751436040-749351 X-HE-Meta: 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 Yi8a4PuC rUdYw4ISvBcrXQi0wxA+2kla0qoLuT5FDO9PRt0xlG426+O0LUFtZNedkmMXurNAO7SX26CRFuG+W2mSlgA8iHI8MphUg8cpIJKp5CRiqz+nxVB7UzU9+CH64eBInGHoS7SWeiIA4mUya5Y4UiQo5DIVqbzMYbuWjaADfz5fBKdDS1UEIh6nUl6rLhxpRWcvrFGDGa2AAT0ru9wz1rzRUD4EQbqZOPdtOTj287lRwSh4NrCOzYm6mL4vkdOt+YZlDUa8voImAHZFUrVlApNmY40jn3aqqmO+1uG9JwVr/VPMSyT65urBAYrMLJHQVJPSj1f+nBP8vDmIRU3tjhDpnZNfWj5tey4efcdryYg6lvRtRFYT7K5ezmaSP1+redVKdBhVgR8FKOU2dVWVbMvdA0+n6BlKfhuz9lHwQzEtqX/QuzF8wR1IrILelW6V70ozxKTIyjljF99BAWENpaHRlLw2+nXNF88NmhwJ9lSUEOLk+pu7jOw6uqOaWOi//EIVa2G4H 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: khugepaged may try to collapse a mTHP to a smaller mTHP, resulting in some pages being unmapped. Skip these cases until we have a way to check if its ok to collapse to a smaller mTHP size (like in the case of a partially mapped folio). This patch is inspired by Dev Jain's work on khugepaged mTHP support [1]. [1] https://lore.kernel.org/lkml/20241216165105.56185-11-dev.jain@arm.com/ Reviewed-by: Baolin Wang Co-developed-by: Dev Jain Signed-off-by: Dev Jain Signed-off-by: Nico Pache --- mm/khugepaged.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index a42f08edb0e4..61d2b3ebc7ac 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -612,7 +612,12 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, folio = page_folio(page); VM_BUG_ON_FOLIO(!folio_test_anon(folio), folio); - /* See hpage_collapse_scan_pmd(). */ + if (order != HPAGE_PMD_ORDER && folio_order(folio) >= order) { + result = SCAN_PTE_MAPPED_HUGEPAGE; + goto out; + } + + /* See khugepaged_scan_pmd(). */ if (folio_maybe_mapped_shared(folio)) { ++shared; if (order != HPAGE_PMD_ORDER || (cc->is_khugepaged && -- 2.49.0