The patch titled
Subject: mm/shmem: restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-shmem-restore-shmem_huge_deny-precedence-over-madv_collapse.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-restore-shmem_huge_deny-precedence-over-madv_collapse.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Zach O'Keefe" <zokeefe@xxxxxxxxxx>
Subject: mm/shmem: restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE
Date: Sat, 24 Dec 2022 00:20:35 -0800
SHMEM_HUGE_DENY is for emergency use by the admin, to disable allocation
of shmem huge pages if, for example, a dangerous bug is found in their
usage: see "deny" in Documentation/mm/transhuge.rst. An app using
madvise(,,MADV_COLLAPSE) should not be allowed to override it: restore its
precedence over shmem_huge_force.
Restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE.
Link: https://lkml.kernel.org/r/20221224082035.3197140-2-zokeefe@xxxxxxxxxx
Fixes: 7c6c6cc4d3a2 ("mm/shmem: add flag to enforce shmem THP in hugepage_vma_check()")
Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>
Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/shmem.c~mm-shmem-restore-shmem_huge_deny-precedence-over-madv_collapse
+++ a/mm/shmem.c
@@ -478,12 +478,10 @@ bool shmem_is_huge(struct vm_area_struct
if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
return false;
- if (shmem_huge_force)
- return true;
- if (shmem_huge == SHMEM_HUGE_FORCE)
- return true;
if (shmem_huge == SHMEM_HUGE_DENY)
return false;
+ if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE)
+ return true;
switch (SHMEM_SB(inode->i_sb)->huge) {
case SHMEM_HUGE_ALWAYS:
_
Patches currently in -mm which might be from zokeefe@xxxxxxxxxx are
mm-madv_collapse-dont-expand-collapse-when-vm_end-is-past-requested-end.patch
mm-shmem-restore-shmem_huge_deny-precedence-over-madv_collapse.patch
