The patch titled
Subject: mm/huge_memory.c: make get_huge_zero_page() return bool
has been added to the -mm tree. Its filename is
mm-huge_memoryc-make-get_huge_zero_page-return-bool.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-huge_memoryc-make-get_huge_zero_page-return-bool.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-huge_memoryc-make-get_huge_zero_page-return-bool.patch
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/huge_memory.c: make get_huge_zero_page() return bool
It's guaranteed that huge_zero_page will not be NULL if huge_zero_refcount
is increased successfully. When READ_ONCE(huge_zero_page) is returned,
there must be a huge_zero_page and it can be replaced with returning
'true' when we do not care about the value of huge_zero_page. We can thus
make it return bool to save READ_ONCE cpu cycles as the return value is
just used to check if huge_zero_page exists.
Link: https://lkml.kernel.org/r/20210318122722.13135-3-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Thomas Hellstrm (Intel) <thomas_os@xxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: yuleixzhang <yulei.kernel@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/huge_memory.c~mm-huge_memoryc-make-get_huge_zero_page-return-bool
+++ a/mm/huge_memory.c
@@ -78,18 +78,18 @@ bool transparent_hugepage_enabled(struct
return false;
}
-static struct page *get_huge_zero_page(void)
+static bool get_huge_zero_page(void)
{
struct page *zero_page;
retry:
if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
- return READ_ONCE(huge_zero_page);
+ return true;
zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
HPAGE_PMD_ORDER);
if (!zero_page) {
count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
- return NULL;
+ return false;
}
count_vm_event(THP_ZERO_PAGE_ALLOC);
preempt_disable();
@@ -102,7 +102,7 @@ retry:
/* We take additional reference here. It will be put back by shrinker */
atomic_set(&huge_zero_refcount, 2);
preempt_enable();
- return READ_ONCE(huge_zero_page);
+ return true;
}
static void put_huge_zero_page(void)
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
hugetlb_cgroup-fix-imbalanced-css_get-and-css_put-pair-for-shared-mappings.patch
hugetlb_cgroup-fix-imbalanced-css_get-and-css_put-pair-for-shared-mappings-v3.patch
mm-hugetlb-remove-redundant-reservation-check-condition-in-alloc_huge_page.patch
mm-hugetlb-use-some-helper-functions-to-cleanup-code.patch
mm-hugetlb-optimize-the-surplus-state-transfer-code-in-move_hugetlb_state.patch
hugetlb_cgroup-remove-unnecessary-vm_bug_on_page-in-hugetlb_cgroup_migrate.patch
mm-hugetlb-simplify-the-code-when-alloc_huge_page-failed-in-hugetlb_no_page.patch
mm-hugetlb-avoid-calculating-fault_mutex_hash-in-truncate_op-case.patch
khugepaged-remove-unneeded-return-value-of-khugepaged_collapse_pte_mapped_thps.patch
khugepaged-reuse-the-smp_wmb-inside-__setpageuptodate.patch
khugepaged-use-helper-khugepaged_test_exit-in-__khugepaged_enter.patch
khugepaged-fix-wrong-result-value-for-trace_mm_collapse_huge_page_isolate.patch
mm-huge_memoryc-remove-unnecessary-local-variable-ret2.patch
mm-huge_memoryc-rework-the-function-vma_adjust_trans_huge.patch
mm-huge_memoryc-make-get_huge_zero_page-return-bool.patch
mm-huge_memoryc-rework-the-function-do_huge_pmd_numa_page-slightly.patch
mm-huge_memoryc-remove-redundant-pagecompound-check.patch
mm-huge_memoryc-remove-unused-macro-transparent_hugepage_debug_cow_flag.patch
mm-huge_memoryc-use-helper-function-migration_entry_to_page.patch
