The patch below does not apply to the 5.15-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 stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 55d134a7b499c77e7cfd0ee41046f3c376e791e5 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024061317-rework-obituary-d23b@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
55d134a7b499 ("mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid") a01f43901cfb ("hugetlb: be sure to free demoted CMA pages to CMA") 79dfc695525f ("hugetlb: add demote hugetlb page sysfs interfaces")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 55d134a7b499c77e7cfd0ee41046f3c376e791e5 Mon Sep 17 00:00:00 2001 From: Frank van der Linden fvdl@google.com Date: Thu, 4 Apr 2024 16:25:15 +0000 Subject: [PATCH] mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid
The hugetlb_cma code passes 0 in the order_per_bit argument to cma_declare_contiguous_nid (the alignment, computed using the page order, is correctly passed in).
This causes a bit in the cma allocation bitmap to always represent a 4k page, making the bitmaps potentially very large, and slower.
It would create bitmaps that would be pretty big. E.g. for a 4k page size on x86, hugetlb_cma=64G would mean a bitmap size of (64G / 4k) / 8 == 2M. With HUGETLB_PAGE_ORDER as order_per_bit, as intended, this would be (64G / 2M) / 8 == 4k. So, that's quite a difference.
Also, this restricted the hugetlb_cma area to ((PAGE_SIZE << MAX_PAGE_ORDER) * 8) * PAGE_SIZE (e.g. 128G on x86) , since bitmap_alloc uses normal page allocation, and is thus restricted by MAX_PAGE_ORDER. Specifying anything about that would fail the CMA initialization.
So, correctly pass in the order instead.
Link: https://lkml.kernel.org/r/20240404162515.527802-2-fvdl@google.com Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma") Signed-off-by: Frank van der Linden fvdl@google.com Acked-by: Roman Gushchin roman.gushchin@linux.dev Acked-by: David Hildenbrand david@redhat.com Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Muchun Song muchun.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 228c886c46c1..5dc3f5ea3a2e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -7794,9 +7794,9 @@ void __init hugetlb_cma_reserve(int order) * huge page demotion. */ res = cma_declare_contiguous_nid(0, size, 0, - PAGE_SIZE << HUGETLB_PAGE_ORDER, - 0, false, name, - &hugetlb_cma[nid], nid); + PAGE_SIZE << HUGETLB_PAGE_ORDER, + HUGETLB_PAGE_ORDER, false, name, + &hugetlb_cma[nid], nid); if (res) { pr_warn("hugetlb_cma: reservation failed: err %d, node %d", res, nid);