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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxHA8-0000000ApKH-2wEA; Tue, 03 Mar 2026 04:15:12 +0000 Date: Tue, 3 Mar 2026 04:15:12 +0000 From: Matthew Wilcox To: "liying3@sungrowpower.com" Cc: akpm , linux-mm , linux-kernel , victor7q , David Hildenbrand , Greg Kroah-Hartman Subject: Re: [BUG] mm/mempolicy: possible double-unlock in migrate_to_node() on 6.6 Message-ID: References: <2026030310525141773825@sungrowpower.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2026030310525141773825@sungrowpower.com> X-Rspamd-Queue-Id: 657B520005 X-Stat-Signature: 4rmk1ohcddye749ewmhkhbdq98mwdmye X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1772511318-77921 X-HE-Meta: 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 Iq2yT7WW prbDloplb6OU+j3LFsAaVJUei8duMDuTry5E5Wr1YpiWvZe2AXd6QxiSvIezObnIQRsjo9BCjdRX0WXbWrL2IihOniYWPUFKVQETfLto3H0+lxbBWl/CKgbjh+cjpOd96KtjzIaWApJejLHMwPcGk9ua2F0s8XCYByjhc6X2XsVy8ly2QWFqoxHKZboER8WNBm+L6A4ZYfVb7Rb4BqsYjaP9d6ezZk7EBLAjlrMCM3ZGh207RxnegXbGJH/4AaXDtL+s+BI8Vw+RLs4+/iJ82VAEovHTwaY/0f0wGjxw4HbZ2fEv9sDRXPZZKn1oOyy9+a3e9j9KPTHax7AfaGo7mKfD1xK/KURqyKxeXiUxUp1vi50FpzS/0i5rLa5XSPMx6TEg7wSf6zQiwy6HmzFkitLQBFRVxSpj1cPdtbGBun4/M7G0FOx94UONgiU++jBcxuvnc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 03, 2026 at 10:52:51AM +0800, liying3@sungrowpower.com wrote: > Hi Andrew, > > I found that a fix is required for this submission in branch 6.6. > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a13b2b9b0b0b04612c7d81e3b3dfb485c5f7abc3 Agreed, although your email should more properly have been directed to David and possibly Greg. Are you going to submit a patch to fix this, or do you prefer that somebody else does it? > Regarding the difference between branches 6.6 and 6.12, in branch 6.6, mmap_read_lock() and mmap_read_unlock() are called outside the migrate_to_node() function. > Therefore, mmap_read_unlock(mm) should not be invoked inside migrate_to_node(); otherwise, it would result in a double unlock of the mm. > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 54f1b78d1b2c0f..94c74c594d102a 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1071,6 +1071,10 @@ static long migrate_to_node(struct mm_struct *mm, int source, int dest, > VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))); > vma = find_vma(mm, 0); > + if (unlikely(!vma)) { > + mmap_read_unlock(mm); // this line should be deleted > + return 0; > + } > /* > * This does not migrate the range, but isolates all pages that > > > > Best Regards, > Li Ying , Light Storage Group. Senior Embedded Software Engineer > Tel: -； Fax: - > Mobile: +86-15651963981 > liying3@sungrowpower.com > www.sungrowpower.com > SUNGROW POWER SUPPLY Co., Ltd. > Add: No.1699 Xiyou Rd., New & High Technology Industrial Development Zone, Hefei, P. R. China., 230088