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mm: khugepaged: avoid pointless allocation for "struct mm_slot" 

In __khugepaged_enter(), if "mm->flags" with MMF_VM_HUGEPAGE bit is set,
the "mm_slot" will be released and return, so we can call mm_slot_alloc()
after test_and_set_bit().

Link: https://lkml.kernel.org/r/20230531095817.11012-1-xhao@linux.alibaba.com
Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foudation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Xin Hao 2023-05-31 17:58:17 +08:00 committed by Andrew Morton
parent 3b11edf1f2
commit 1661867027
1 changed files with 5 additions and 7 deletions
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12
mm/khugepaged.c
View File

@ -422,19 +422,17 @@ void __khugepaged_enter(struct mm_struct *mm)
struct mm_slot *slot;
int wakeup;
/* __khugepaged_exit() must not run from under us */
VM_BUG_ON_MM(hpage_collapse_test_exit(mm), mm);
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags)))
return;
mm_slot = mm_slot_alloc(mm_slot_cache);
if (!mm_slot)
return;
slot = &mm_slot->slot;
/* __khugepaged_exit() must not run from under us */
VM_BUG_ON_MM(hpage_collapse_test_exit(mm), mm);
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
mm_slot_free(mm_slot_cache, mm_slot);
return;
}
spin_lock(&khugepaged_mm_lock);
mm_slot_insert(mm_slots_hash, mm, slot);
/*