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...
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@google.com 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@google.com Fixes: 7c6c6cc4d3a2 ("mm/shmem: add flag to enforce shmem THP in hugepage_vma_check()") Signed-off-by: Zach O'Keefe zokeefe@google.com Suggested-by: Hugh Dickins hughd@google.com Cc: Yang Shi shy828301@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
--- 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@google.com 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