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Tue, 2 Aug 2022 23:09:25 +0800 From: Kefeng Wang To: Andrew Morton , CC: , Kefeng Wang , Abhishek Shah , Gabriel Ryan Subject: [PATCH] mm: ksm: fix data-race in __ksm_enter / run_store Date: Tue, 2 Aug 2022 23:15:50 +0800 Message-ID: <20220802151550.159076-1-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659452972; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references; bh=47SM2RNcLoH2WgPd/g9e0YPCfApw265hzMp9PkPC+IE=; b=cJGIfbH87C7NR6ZOcb09yylAj6MLU7p8TtQv9n8+m5+ItPwj7mggBCxb7pIdtK0Rz07Clt 3PSvPNuyXT2uOxXP4RgdeYz6jZOtuY6LFIHI7OFG2OONSzeLO/CGz21vyx9rfcFJ9tLx4m 4EGpVQcmEnGuH/Z9Q0U9rEBBCgJEbfA= ARC-Authentication-Results: i=1; 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Reported-and-tested-by: Abhishek Shah Cc: Gabriel Ryan Signed-off-by: Kefeng Wang --- mm/ksm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/ksm.c b/mm/ksm.c index 2f315c69fa2c..3f1908946a6f 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2507,6 +2507,7 @@ int __ksm_enter(struct mm_struct *mm) { struct mm_slot *mm_slot; int needs_wakeup; + bool ksm_run_unmerge; mm_slot = alloc_mm_slot(); if (!mm_slot) @@ -2515,6 +2516,10 @@ int __ksm_enter(struct mm_struct *mm) /* Check ksm_run too? Would need tighter locking */ needs_wakeup = list_empty(&ksm_mm_head.mm_list); + mutex_lock(&ksm_thread_mutex); + ksm_run_unmerge = !!(ksm_run & KSM_RUN_UNMERGE); + mutex_unlock(&ksm_thread_mutex); + spin_lock(&ksm_mmlist_lock); insert_to_mm_slots_hash(mm, mm_slot); /* @@ -2527,7 +2532,7 @@ int __ksm_enter(struct mm_struct *mm) * scanning cursor, otherwise KSM pages in newly forked mms will be * missed: then we might as well insert at the end of the list. */ - if (ksm_run & KSM_RUN_UNMERGE) + if (ksm_run_unmerge) list_add_tail(&mm_slot->mm_list, &ksm_mm_head.mm_list); else list_add_tail(&mm_slot->mm_list, &ksm_scan.mm_slot->mm_list);