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b=ot/UjyE5Ao50Gqfx4Je4I7eGFBq0LXPXz2hgqVLW8paphcUPcSfSro8OcnBQY6wSb zlc+fH7ND9/dsvS8G5aTrL9XYXYLAe/Gg56tMMh/pTjGLqJR+fA+qm4E/4aNP6tHvA Dy0fDQscS0ylRDSN3ILlAmseZOv0dW79ya18p4te4XuKeo+G269QJlnKPFX4cisQUL +7gthlmfnXohRfNao0z9bdmeHalrgh2zQNiak229+8tA4/idLg24Qiywb6Ov+RW0Zm suaLGh2mb265nDnvSer+I7LG6pjylrbgpE8L03QXmlckRu/6wnywkLEqsGzprh+erd K9fFyBTOdQNjA== From: Sasha Levin To: stable@vger.kernel.org, vbabka@kernel.org Cc: Vlastimil Babka , Michal Hocko , Johannes Weiner , Pedro Falcato , Zi Yan , Brendan Jackman , "David Hildenbrand (Red Hat)" , David Rientjes , Joshua Hahn , Liam Howlett , Lorenzo Stoakes , Mike Rapoport , Suren Baghdasaryan , Andrew Morton , linux-mm@kvack.org Subject: FAILED: Patch "mm, page_alloc, thp: prevent reclaim for __GFP_THISNODE THP allocations" failed to apply to 6.6-stable tree Date: Sat, 28 Feb 2026 20:33:43 -0500 Message-ID: <20260301013344.1693034-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 21342C0007 X-Rspamd-Server: rspam08 X-Stat-Signature: gmar7tuxqeqdw1odnpbb3c4e5odp6agr X-HE-Tag: 1772328827-21083 X-HE-Meta: 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 Z4KWThTC NoDEgOCk0Jv6h+Vca9jGAKbDBYqPEpdXFa6DiALhgazNckc0heEM3CvLZt3AWU3bZASQOHeZukhXF4imJwyJLkjUDiNhX+t9kfViK/q80IN8xtre5QZL8uMpZ2/D2ZkoV7MchBZ69ajovmbs2+R6iJ1JEohbntR3xVfLk9EH1JLtiq2icAwPguoD/jXLniocV70hpd0rbZGw5NA+/fNTxMsNmG331W6GDz4zlK9OJD5yb6p5q2ANSv75R2DOP2GLFA8pScUdXKs3h+U9ZkZm1x2i5KeUn7AhzqlIO3O5bN5/ogUqiO2t+Q9SixjECNcN8mqlg7wpWowrAIeQLloP5srBUQNE2MXFVkyOUM1dlk+18Sru7ZRrcwCMjaoFof066tQr2pt33Li7rB7mXIJmZEHv4NmVo8Dup2uba5dlmrNDd/mJ9Kikj9LDiT1LQq9aq6LOMnHcxnaPQMo1R5A7V0gtFC1a+WOVJhYGoyZHtPoujlkY5QC7CZ6gXHj6alEGvEAL+9fQ1Bx9RDlWfrKMLONL24gB7oYHJLVQPEn3ZUzZSmN3gMmi91XHAEYXXBpViEZ7wihiFpbdhwgJ+mA7wJyqocPlfwK58okfZDCStE0Ntb1baMzWyjASaTA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 9c9828d3ead69416d731b1238802af31760c823e Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Fri, 19 Dec 2025 17:31:57 +0100 Subject: [PATCH] mm, page_alloc, thp: prevent reclaim for __GFP_THISNODE THP allocations Since commit cc638f329ef6 ("mm, thp: tweak reclaim/compaction effort of local-only and all-node allocations"), THP page fault allocations have settled on the following scheme (from the commit log): 1. local node only THP allocation with no reclaim, just compaction. 2. for madvised VMA's or when synchronous compaction is enabled always - THP allocation from any node with effort determined by global defrag setting and VMA madvise 3. fallback to base pages on any node Recent customer reports however revealed we have a gap in step 1 above. What we have seen is excessive reclaim due to THP page faults on a NUMA node that's close to its high watermark, while other nodes have plenty of free memory. The problem with step 1 is that it promises no reclaim after the compaction attempt, however reclaim is only avoided for certain compaction outcomes (deferred, or skipped due to insufficient free base pages), and not e.g. when compaction is actually performed but fails (we did see compact_fail vmstat counter increasing). THP page faults can therefore exhibit a zone_reclaim_mode-like behavior, which is not the intention. Thus add a check for __GFP_THISNODE that corresponds to this exact situation and prevents continuing with reclaim/compaction once the initial compaction attempt isn't successful in allocating the page. Note that commit cc638f329ef6 has not introduced this over-reclaim possibility; it appears to exist in some form since commit 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations"). Followup commits b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction may not succeed") and cc638f329ef6 have moved in the right direction, but left the abovementioned gap. Link: https://lkml.kernel.org/r/20251219-costly-noretry-thisnode-fix-v1-1-e1085a4a0c34@suse.cz Fixes: 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations") Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko Acked-by: Johannes Weiner Acked-by: Pedro Falcato Acked-by: Zi Yan Cc: Brendan Jackman Cc: "David Hildenbrand (Red Hat)" Cc: David Rientjes Cc: Joshua Hahn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton --- mm/page_alloc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e1cc0c9ed9479..3333524e879c4 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4818,6 +4818,20 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, compact_result == COMPACT_DEFERRED) goto nopage; + /* + * THP page faults may attempt local node only first, + * but are then allowed to only compact, not reclaim, + * see alloc_pages_mpol(). + * + * Compaction can fail for other reasons than those + * checked above and we don't want such THP allocations + * to put reclaim pressure on a single node in a + * situation where other nodes might have plenty of + * available memory. + */ + if (gfp_mask & __GFP_THISNODE) + goto nopage; + /* * Looks like reclaim/compaction is worth trying, but * sync compaction could be very expensive, so keep -- 2.51.0