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[2a03:2880:20ff:11::face:b00c]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6c162db0b30sm111696d6.77.2024.08.21.12.35.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Aug 2024 12:35:51 -0700 (PDT) From: Usama Arif To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, riel@surriel.com, zhaoyang.huang@unisoc.com, yuzhao@google.com, david@redhat.com, leitao@debian.org, huangzhaoyang@gmail.com, bharata@amd.com, willy@infradead.org, vbabka@suse.cz, linux-kernel@vger.kernel.org, kernel-team@meta.com, Usama Arif Subject: [PATCH] Revert "mm: skip CMA pages when they are not available" Date: Wed, 21 Aug 2024 20:35:06 +0100 Message-ID: <20240821193506.1525996-1-usamaarif642@gmail.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b. lruvec->lru_lock is highly contended and is held when calling isolate_lru_folios. If the lru has a large number of CMA folios consecutively, while the allocation type requested is not MIGRATE_MOVABLE, isolate_lru_folios can hold the lock for a very long time while it skips those. For FIO workload, ~150million order=3D0 folios were skipped to isolate a few ZONE_DMA folios [1]. This can cause lockups [1] and high memory pressure for extended periods of time [2]. [1] https://lore.kernel.org/all/CAOUHufbkhMZYz20aM_3rHZ3OcK4m2puji2FGpUpn_-= DevGk3Kg@mail.gmail.com/ [2] https://lore.kernel.org/all/ZrssOrcJIDy8hacI@gmail.com/ Signed-off-by: Usama Arif Acked-by: Johannes Weiner --- mm/vmscan.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 5dc96a843466..78ad4a141409 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1690,8 +1690,7 @@ static unsigned long isolate_lru_folios(unsigned long= nr_to_scan, nr_pages =3D folio_nr_pages(folio); total_scan +=3D nr_pages; =20 - if (folio_zonenum(folio) > sc->reclaim_idx || - skip_cma(folio, sc)) { + if (folio_zonenum(folio) > sc->reclaim_idx) { nr_skipped[folio_zonenum(folio)] +=3D nr_pages; move_to =3D &folios_skipped; goto move; --=20 2.43.5