[PATCH RFC 06/37] mm: page_alloc: Allocate from movable pcp lists only if ALLOC_FROM_METADATA
From: Alexandru Elisei <hidden>
Date: 2023-08-23 13:15:16
Also in:
kvmarm, linux-arch, linux-fsdevel, linux-mm, linux-trace-kernel, lkml
Subsystem:
memory management, memory management - page allocator, the rest · Maintainers:
Andrew Morton, Vlastimil Babka, Linus Torvalds
pcp lists keep MIGRATE_METADATA pages on the MIGRATE_MOVABLE list. Make sure pages from the movable list are allocated only when the ALLOC_FROM_METADATA alloc flag is set, as otherwise the page allocator could end up allocating a metadata page when that page cannot be used. __alloc_pages_bulk() sidesteps rmqueue() and calls __rmqueue_pcplist() directly. Add a check for the flag before calling __rmqueue_pcplist(), and fallback to __alloc_pages() if the check is false. Note that CMA isn't a problem for __alloc_pages_bulk(): an allocation can always use CMA pages if the requested migratetype is MIGRATE_MOVABLE, which is not the case with MIGRATE_METADATA pages. Signed-off-by: Alexandru Elisei <redacted> --- mm/page_alloc.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 829134a4dfa8..a693e23c4733 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -2845,11 +2845,16 @@ struct page *rmqueue(struct zone *preferred_zone, if (likely(pcp_allowed_order(order))) { /* - * MIGRATE_MOVABLE pcplist could have the pages on CMA area and - * we need to skip it when CMA area isn't allowed. + * PCP lists keep MIGRATE_CMA/MIGRATE_METADATA pages on the same + * movable list. Make sure it's allowed to allocate both type of + * pages before allocating from the movable list. */ - if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA || - migratetype != MIGRATE_MOVABLE) { + bool movable_allowed = (!IS_ENABLED(CONFIG_CMA) || + (alloc_flags & ALLOC_CMA)) && + (!IS_ENABLED(CONFIG_MEMORY_METADATA) || + (alloc_flags & ALLOC_FROM_METADATA)); + + if (migratetype != MIGRATE_MOVABLE || movable_allowed) { page = rmqueue_pcplist(preferred_zone, zone, order, migratetype, alloc_flags); if (likely(page))
@@ -4388,6 +4393,14 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, goto out; gfp = alloc_gfp; + /* + * pcp lists puts MIGRATE_METADATA on the MIGRATE_MOVABLE list, don't + * use pcp if allocating metadata pages is not allowed. + */ + if (metadata_storage_enabled() && ac.migratetype == MIGRATE_MOVABLE && + !(alloc_flags & ALLOC_FROM_METADATA)) + goto failed; + /* Find an allowed local zone that meets the low watermark. */ for_each_zone_zonelist_nodemask(zone, z, ac.zonelist, ac.highest_zoneidx, ac.nodemask) { unsigned long mark;
--
2.41.0
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