The quilt patch titled Subject: Revert "mm: skip CMA pages when they are not available" has been removed from the -mm tree. Its filename was revert-mm-skip-cma-pages-when-they-are-not-available.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Usama Arif usamaarif642@gmail.com Subject: Revert "mm: skip CMA pages when they are not available" Date: Wed, 21 Aug 2024 20:26:07 +0100

This reverts commit 5da226dbfce3 ("mm: skip CMA pages when they are not available") and b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible").

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=0 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].

Remove skipping CMA for MGLRU as well, as it was introduced in sort_folio for the same resaon as 5da226dbfce3a2f44978c2c7cf88166e69a6788b.

[1] https://lore.kernel.org/all/CAOUHufbkhMZYz20aM_3rHZ3OcK4m2puji2FGpUpn_-DevGk... [2] https://lore.kernel.org/all/ZrssOrcJIDy8hacI@gmail.com/

[usamaarif642@gmail.com: also revert b7108d66318a, per Johannes] Link: https://lkml.kernel.org/r/9060a32d-b2d7-48c0-8626-1db535653c54@gmail.com Link: https://lkml.kernel.org/r/357ac325-4c61-497a-92a3-bdbd230d5ec9@gmail.com Link: https://lkml.kernel.org/r/9060a32d-b2d7-48c0-8626-1db535653c54@gmail.com Fixes: 5da226dbfce3 ("mm: skip CMA pages when they are not available") Signed-off-by: Usama Arif usamaarif642@gmail.com Acked-by: Johannes Weiner hannes@cmpxchg.org Cc: Bharata B Rao bharata@amd.com Cc: Breno Leitao leitao@debian.org Cc: David Hildenbrand david@redhat.com Cc: Matthew Wilcox willy@infradead.org Cc: Rik van Riel riel@surriel.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Yu Zhao yuzhao@google.com Cc: Zhaoyang Huang huangzhaoyang@gmail.com Cc: Zhaoyang Huang zhaoyang.huang@unisoc.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/vmscan.c | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-)

--- a/mm/vmscan.c~revert-mm-skip-cma-pages-when-they-are-not-available +++ a/mm/vmscan.c @@ -1604,25 +1604,6 @@ static __always_inline void update_lru_s

}

-#ifdef CONFIG_CMA -/* - * It is waste of effort to scan and reclaim CMA pages if it is not available - * for current allocation context. Kswapd can not be enrolled as it can not - * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL - */ -static bool skip_cma(struct folio *folio, struct scan_control *sc) -{ - return !current_is_kswapd() && - gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE && - folio_migratetype(folio) == MIGRATE_CMA; -} -#else -static bool skip_cma(struct folio *folio, struct scan_control *sc) -{ - return false; -} -#endif - /* * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. * @@ -1669,8 +1650,7 @@ static unsigned long isolate_lru_folios( nr_pages = folio_nr_pages(folio); total_scan += nr_pages;

- if (folio_zonenum(folio) > sc->reclaim_idx || - skip_cma(folio, sc)) { + if (folio_zonenum(folio) > sc->reclaim_idx) { nr_skipped[folio_zonenum(folio)] += nr_pages; move_to = &folios_skipped; goto move; @@ -4320,7 +4300,7 @@ static bool sort_folio(struct lruvec *lr }

/* ineligible */ - if (zone > sc->reclaim_idx || skip_cma(folio, sc)) { + if (zone > sc->reclaim_idx) { gen = folio_inc_gen(lruvec, folio, false); list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); return true; _

Patches currently in -mm which might be from usamaarif642@gmail.com are

mm-store-zero-pages-to-be-swapped-out-in-a-bitmap.patch mm-remove-code-to-handle-same-filled-pages.patch mm-introduce-a-pageflag-for-partially-mapped-folios.patch mm-split-underused-thps.patch mm-add-sysfs-entry-to-disable-splitting-underused-thps.patch