The patch titled
Subject: mm: mmap: register suitable readonly file vmas for khugepaged
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Yang Shi <shy828301@xxxxxxxxx>
Subject: mm: mmap: register suitable readonly file vmas for khugepaged
The readonly FS THP relies on khugepaged to collapse THP for suitable
vmas. But the behavior is inconsistent for "always" mode
(https://lore.kernel.org/linux-mm/00f195d4-d039-3cf2-d3a1-a2c88de397a0@xxxxxxx/).
The "always" mode means THP allocation should be tried all the time and
khugepaged should try to collapse THP all the time. Of course the
allocation and collapse may fail due to other factors and conditions.
Currently file THP may not be collapsed by khugepaged even though all the
conditions are met. That does break the semantics of "always" mode.
So make sure readonly FS vmas are registered to khugepaged to fix the
break.
Register suitable vmas in common mmap path, that could cover both readonly
FS vmas and shmem vmas, so remove the khugepaged calls in shmem.c.
Still need to keep the khugepaged call in vma_merge() since vma_merge() is
called in a lot of places, for example, madvise, mprotect, etc.
Link: https://lkml.kernel.org/r/20220510203222.24246-9-shy828301@xxxxxxxxx
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Vlastmil Babka <vbabka@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 6 ++++++
mm/shmem.c | 4 ----
2 files changed, 6 insertions(+), 4 deletions(-)
--- a/mm/mmap.c~mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged
+++ a/mm/mmap.c
@@ -2745,6 +2745,12 @@ cannot_expand:
i_mmap_unlock_write(vma->vm_file->f_mapping);
}
+ /*
+ * vma_merge() calls khugepaged_enter_vma() either, the below
+ * call covers the non-merge case.
+ */
+ khugepaged_enter_vma(vma, vma->vm_flags);
+
/* Once vma denies write, undo our temporary denial count */
unmap_writable:
if (file && vm_flags & VM_SHARED)
--- a/mm/shmem.c~mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged
+++ a/mm/shmem.c
@@ -34,7 +34,6 @@
#include <linux/export.h>
#include <linux/swap.h>
#include <linux/uio.h>
-#include <linux/khugepaged.h>
#include <linux/hugetlb.h>
#include <linux/fs_parser.h>
#include <linux/swapfile.h>
@@ -2232,7 +2231,6 @@ static int shmem_mmap(struct file *file,
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
- khugepaged_enter_vma(vma, vma->vm_flags);
return 0;
}
@@ -4133,8 +4131,6 @@ int shmem_zero_setup(struct vm_area_stru
vma->vm_file = file;
vma->vm_ops = &shmem_vm_ops;
- khugepaged_enter_vma(vma, vma->vm_flags);
-
return 0;
}
_
Patches currently in -mm which might be from shy828301@xxxxxxxxx are
sched-coredumph-clarify-the-use-of-mmf_vm_hugepage.patch
mm-khugepaged-remove-redundant-check-for-vm_no_khugepaged.patch
mm-khugepaged-skip-dax-vma.patch
mm-thp-only-regular-file-could-be-thp-eligible.patch
mm-khugepaged-make-khugepaged_enter-void-function.patch
mm-khugepaged-make-hugepage_vma_check-non-static.patch
mm-khugepaged-introduce-khugepaged_enter_vma-helper.patch
mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged.patch
