From 16618670276a77480e274117992cec5e42ce66a9 Mon Sep 17 00:00:00 2001 From: Xin Hao Date: Wed, 31 May 2023 17:58:17 +0800 Subject: [PATCH] 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 Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton --- mm/khugepaged.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 6b9d39d65b730..3649ba12a2355 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -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); /* -- 2.30.2