FAILED: patch "[PATCH] migrate: hugetlb: check for hugetlb shared PMD in node" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-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 <[email protected]>.

Possible dependencies:

73bdf65ea748 ("migrate: hugetlb: check for hugetlb shared PMD in node migration") 7ce82f4c3f3e ("mm/migration: return errno when isolate_huge_page failed") 1b7f7e58decc ("mm/gup: Convert check_and_migrate_movable_pages() to use a folio") f9f38f78c5d5 ("mm: refactor check_and_migrate_movable_pages")
5ac95884a784 ("mm/migrate: enable returning precise migrate_pages() success count") c5b5a3dd2c1f ("mm: thp: refactor NUMA fault handling")
5db4f15c4fd7 ("mm: memory: add orig_pmd to struct vm_fault")
8f34f1eac382 ("mm/userfaultfd: fix uffd-wp special cases for fork()") 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation") f68749ec342b ("mm/gup: longterm pin migration cleanup")
d1e153fea2a8 ("mm/gup: migrate pinned pages out of movable zone") 1a08ae36cf8b ("mm cma: rename PF_MEMALLOC_NOCMA to PF_MEMALLOC_PIN") 6e7f34ebb8d2 ("mm/gup: check for isolation errors")
f0f4463837da ("mm/gup: return an error on migration failure")
83c02c23d074 ("mm/gup: check every subpage of a compound page during isolation") c991ffef7bce ("mm/gup: don't pin migrated cma pages in movable zone") 7ee820ee7238 ("Revert "mm: migrate: skip shared exec THP for NUMA balancing"") ae37c7ff79f1 ("mm: make alloc_contig_range handle in-use hugetlb pages") 369fa227c219 ("mm: make alloc_contig_range handle free hugetlb pages") c2ad7a1ffeaf ("mm,compaction: let isolate_migratepages_{range,block} return error codes")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 73bdf65ea74857d7fb2ec3067a3cec0e261b1462 Mon Sep 17 00:00:00 2001
From: Mike Kravetz <[email protected]>
Date: Thu, 26 Jan 2023 14:27:21 -0800
Subject: [PATCH] migrate: hugetlb: check for hugetlb shared PMD in node
migration

migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required to move pages shared with another process to a different node. page_mapcount

hugetlb page will have a mapcount of 1 if mapped by multiple processes via a shared PMD. As a result, hugetlb pages shared by multiple processes and mapped with a shared PMD can be moved by a process without CAP_SYS_NICE.

To fix, check for a shared PMD if mapcount is 1. If a shared PMD is found consider the page shared.

index 02c8a712282f..f940395667c8 100644
@@ -600,7 +600,8 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
 
 	/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
 	if (flags & (MPOL_MF_MOVE_ALL) ||
-	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1)) {
+	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 &&
+	     !hugetlb_pmd_shared(pte))) {
 		if (isolate_hugetlb(page, qp->pagelist) &&
 			(flags & MPOL_MF_STRICT))
 			/*

Updated patch below. Note that this depends on backport of upstream commit 3489dbb696d25602aea8c3e669a6d43b76bd5358 which is already queued up for 5.4-stable tree.

From 4e75ce608386f0a641455580b05e0a41d1dbba3b Mon Sep 17 00:00:00 2001
From: Mike Kravetz <[email protected]>
Date: Thu, 26 Jan 2023 14:27:21 -0800
Subject: [PATCH] migrate: hugetlb: check for hugetlb shared PMD in node
migration

commit 73bdf65ea74857d7fb2ec3067a3cec0e261b1462 upstream.

migrate_pages/mempolicy semantics state that CAP_SYS_NICE is required to move pages shared with another process to a different node. page_mapcount

hugetlb page will have a mapcount of 1 if mapped by multiple processes via a shared PMD. As a result, hugetlb pages shared by multiple processes and mapped with a shared PMD can be moved by a process without CAP_SYS_NICE.

To fix, check for a shared PMD if mapcount is 1. If a shared PMD is found consider the page shared.

---
 mm/mempolicy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index f7b231f67156..36c2a9619ba5 100644
@@ -571,7 +571,8 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
 		goto unlock;
 	/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
 	if (flags & (MPOL_MF_MOVE_ALL) ||
-	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
+	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 &&
+	     !hugetlb_pmd_shared(pte)))
 		isolate_huge_page(page, qp->pagelist);
 unlock:
 	spin_unlock(ptl);

2.39.1

All now queued up, thanks!

greg k-h