The patch titled
Subject: sched: coredump.h: clarify the use of MMF_VM_HUGEPAGE
has been added to the -mm tree. Its filename is
sched-coredumph-clarify-the-use-of-mmf_vm_hugepage.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/sched-coredumph-clarify-the-use-of-mmf_vm_hugepage.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/sched-coredumph-clarify-the-use-of-mmf_vm_hugepage.patch
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From: Yang Shi <shy828301@xxxxxxxxx>
Subject: sched: coredump.h: clarify the use of MMF_VM_HUGEPAGE
Patch series "Make khugepaged collapse readonly FS THP more consistent", v3.
The readonly FS THP relies on khugepaged to collapse THP for suitable
vmas. But it is kind of "random luck" for khugepaged to see the readonly
FS vmas (see report:
https://lore.kernel.org/linux-mm/00f195d4-d039-3cf2-d3a1-a2c88de397a0@xxxxxxx/)
since currently the vmas are registered to khugepaged when:
- Anon huge pmd page fault
- VMA merge
- MADV_HUGEPAGE
- Shmem mmap
If the above conditions are not met, even though khugepaged is enabled it
won't see readonly FS vmas at all. MADV_HUGEPAGE could be specified
explicitly to tell khugepaged to collapse this area, but when khugepaged
mode is "always" it should scan suitable vmas as long as VM_NOHUGEPAGE is
not set.
So make sure readonly FS vmas are registered to khugepaged to make the
behavior more consistent.
Registering suitable vmas in common mmap path, that could cover both
readonly FS vmas and shmem vmas, so removed the khugepaged calls in
shmem.c.
Patches 1 ~ 7 are minor bug fixes, clean up and preparation patches.
Patch 8 is the real meat.
Tested with khugepaged test in selftests and the testcase provided by
Vlastimil Babka in
https://lore.kernel.org/lkml/df3b5d1c-a36b-2c73-3e27-99e74983de3a@xxxxxxx/
by commenting out MADV_HUGEPAGE call.
This patch (of 8):
MMF_VM_HUGEPAGE is set as long as the mm is available for khugepaged by
khugepaged_enter(), not only when VM_HUGEPAGE is set on vma. Correct the
comment to avoid confusion.
Link: https://lkml.kernel.org/r/20220404200250.321455-1-shy828301@xxxxxxxxx
Link: https://lkml.kernel.org/r/20220404200250.321455-2-shy828301@xxxxxxxxx
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched/coredump.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/linux/sched/coredump.h~sched-coredumph-clarify-the-use-of-mmf_vm_hugepage
+++ a/include/linux/sched/coredump.h
@@ -57,7 +57,8 @@ static inline int get_dumpable(struct mm
#endif
/* leave room for more dump flags */
#define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */
-#define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */
+#define MMF_VM_HUGEPAGE 17 /* set when mm is available for
+ khugepaged */
/*
* This one-shot flag is dropped due to necessity of changing exe once again
* on NFS restore
_
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-move-some-khugepaged_-functions-to-khugepagedc.patch
mm-khugepaged-introduce-khugepaged_enter_vma-helper.patch
mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged.patch
