The quilt patch titled Subject: mm/contig_alloc: fix alloc_contig_range when __GFP_COMP and order < MAX_ORDER has been removed from the -mm tree. Its filename was mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------ From: Jinjiang Tu tujinjiang@huawei.com Subject: mm/contig_alloc: fix alloc_contig_range when __GFP_COMP and order < MAX_ORDER Date: Wed, 12 Mar 2025 16:47:05 +0800

When calling alloc_contig_range() with __GFP_COMP and the order of requested pfn range is pageblock_order, less than MAX_ORDER, I triggered WARNING as follows:

PFN range: requested [2150105088, 2150105600), allocated [2150105088, 2150106112) WARNING: CPU: 3 PID: 580 at mm/page_alloc.c:6877 alloc_contig_range+0x280/0x340

alloc_contig_range() marks pageblocks of the requested pfn range to be isolated, migrate these pages if they are in use and will be freed to MIGRATE_ISOLATED freelist.

Suppose two alloc_contig_range() calls at the same time and the requested pfn range are [0x80280000, 0x80280200) and [0x80280200, 0x80280400) respectively. Suppose the two memory range are in use, then alloc_contig_range() will migrate and free these pages to MIGRATE_ISOLATED freelist. __free_one_page() will merge MIGRATE_ISOLATE buddy to larger buddy, resulting in a MAX_ORDER buddy. Finally, find_large_buddy() in alloc_contig_range() returns a MAX_ORDER buddy and results in WARNING.

To fix it, call free_contig_range() to free the excess pfn range.

Link: https://lkml.kernel.org/r/20250312084705.2938220-1-tujinjiang@huawei.com Fixes: e98337d11bbd ("mm/contig_alloc: support __GFP_COMP") Signed-off-by: Jinjiang Tu tujinjiang@huawei.com Cc: David Hildenbrand david@redhat.com Cc: Kefeng Wang wangkefeng.wang@huawei.com Cc: Nanyong Sun sunnanyong@huawei.com Cc: Yu Zhao yuzhao@google.com Cc: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/page_alloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/mm/page_alloc.c~mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order +++ a/mm/page_alloc.c @@ -6786,7 +6786,8 @@ int alloc_contig_range_noprof(unsigned l goto done; }

- if (!(gfp_mask & __GFP_COMP)) { + if (!(gfp_mask & __GFP_COMP) || + (is_power_of_2(end - start) && ilog2(end - start) < MAX_PAGE_ORDER)) { split_free_pages(cc.freepages, gfp_mask);

/* Free head and tail (if any) */ @@ -6794,7 +6795,15 @@ int alloc_contig_range_noprof(unsigned l free_contig_range(outer_start, start - outer_start); if (end != outer_end) free_contig_range(end, outer_end - end); - } else if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { + + outer_start = start; + outer_end = end; + + if (!(gfp_mask & __GFP_COMP)) + goto done; + } + + if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { struct page *head = pfn_to_page(start); int order = ilog2(end - start);

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Patches currently in -mm which might be from tujinjiang@huawei.com are