6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kirill A. Shutemov kirill.shutemov@linux.intel.com
commit 800f1059c99e2b39899bdc67a7593a7bea6375d8 upstream.
Watermarks are initialized during the postcore initcall. Until then, all watermarks are set to zero. This causes cond_accept_memory() to incorrectly skip memory acceptance because a watermark of 0 is always met.
This can lead to a premature OOM on boot.
To ensure progress, accept one MAX_ORDER page if the watermark is zero.
Link: https://lkml.kernel.org/r/20250310082855.2587122-1-kirill.shutemov@linux.int... Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory") Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Tested-by: Farrah Chen farrah.chen@intel.com Reported-by: Farrah Chen farrah.chen@intel.com Acked-by: Vlastimil Babka vbabka@suse.cz Reviewed-by: Pankaj Gupta pankaj.gupta@amd.com Cc: Ashish Kalra ashish.kalra@amd.com Cc: David Hildenbrand david@redhat.com Cc: "Edgecombe, Rick P" rick.p.edgecombe@intel.com Cc: Mel Gorman mgorman@techsingularity.net Cc: "Mike Rapoport (IBM)" rppt@kernel.org Cc: Thomas Lendacky thomas.lendacky@amd.com Cc: stable@vger.kernel.org [6.5+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/page_alloc.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
--- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6653,7 +6653,7 @@ static bool try_to_accept_memory_one(str
static bool cond_accept_memory(struct zone *zone, unsigned int order) { - long to_accept; + long to_accept, wmark; bool ret = false;
if (!has_unaccepted_memory()) @@ -6662,8 +6662,18 @@ static bool cond_accept_memory(struct zo if (list_empty(&zone->unaccepted_pages)) return false;
+ wmark = high_wmark_pages(zone); + + /* + * Watermarks have not been initialized yet. + * + * Accepting one MAX_ORDER page to ensure progress. + */ + if (!wmark) + return try_to_accept_memory_one(zone); + /* How much to accept to get to high watermark? */ - to_accept = high_wmark_pages(zone) - + to_accept = wmark - (zone_page_state(zone, NR_FREE_PAGES) - __zone_watermark_unusable_free(zone, order, 0) - zone_page_state(zone, NR_UNACCEPTED));