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AJvYcCX5lyfYJrrRf3rXpV00rQ84aZ8HYNYJLHs1UuNPbHA1wkK66O0ZzE8Q03mH5XjziRAHKS3L/rOZQG3qYYPFsW7dVr4= X-Gm-Message-State: AOJu0Yw+whQKDTk8TZHPtGIZ4j2X11ReGQY2ADS7+Gaej862RqPIYfoL e0iOtHMsDEzIPvYoJ+4Id12215N7M4I2mc78DGo4uRNp1jFaosP+7nMB7rzrt1XtkEV3BUvDLeF IHl3l67MX2vqp7JOGdmgSLpOwPRE= X-Google-Smtp-Source: AGHT+IG15zlh+lCtXaMz7BpFoslec2WYJbCbU8nDBzFG6htRZfLeCw6IvXRIohIVvjbp1+iRfiXytcW2o5/LX0Obopg= X-Received: by 2002:a05:651c:221f:b0:2ec:1042:fafc with SMTP id 38308e7fff4ca-2ec1042fbdemr87438671fa.0.1718682148958; Mon, 17 Jun 2024 20:42:28 -0700 (PDT) MIME-Version: 1.0 References: <20240618020926.1911903-1-zhaoyang.huang@unisoc.com> In-Reply-To: From: Zhaoyang Huang Date: Tue, 18 Jun 2024 11:42:17 +0800 Message-ID: Subject: Re: [PATCH] mm: fix hard lockup in __split_huge_page To: Matthew Wilcox Cc: "zhaoyang.huang" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, steve.kang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2D96C1A0005 X-Stat-Signature: m1jrqau1f6scswzhf56n7enogzkimhwn X-HE-Tag: 1718682150-320138 X-HE-Meta: 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 +M3Jr8Fc jlYap7WFQoYtKdqWAi33EfBir0P1N1Qc4n9dp1sFj6NlhEXhZ6QiU0LhyXPemGswDO3q2i4x1jHQs7RT1yRfDatw42f8XNEfD6l/ffjpMN1Jhg1p99gNz22l7Pcv2gwLamPRVea8wzOt/mIrUsZqkJemZv/OKgHKJfrcQ1iSMIuKC66Ze13/CvXCfg03z7x3kneFGFrtKv4g73uOL49hhYmx5quHBKdPEpv+jl5kh6C9Aq41cUwWzkcUSnsAfAEl3d9s8D68rIpxWiF6Snt1g5/QEObwXuzP3xqn4ZG8jsI+7TqmPeXSdun3aylMOK/2K9aayIbRGt9vgBw7p3cE6afTUEfnqKsDg+dAUawABeZbSw5qoHxOz3AGCKn59qny0WfR9+SRT+oTeujhkTqlUG59W6IAShts7eHcxl2Dbe4+udaH4D/jQCNEHbKCoGAB+fPMz X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 18, 2024 at 11:31=E2=80=AFAM Matthew Wilcox wrote: > > On Tue, Jun 18, 2024 at 11:27:12AM +0800, Zhaoyang Huang wrote: > > On Tue, Jun 18, 2024 at 11:19=E2=80=AFAM Matthew Wilcox wrote: > > > > > > On Tue, Jun 18, 2024 at 10:09:26AM +0800, zhaoyang.huang wrote: > > > > Hard lockup[2] is reported which should be caused by recursive > > > > lock contention of lruvec->lru_lock[1] within __split_huge_page. > > > > > > > > [1] > > > > static void __split_huge_page(struct page *page, struct list_head *= list, > > > > pgoff_t end, unsigned int new_order) > > > > { > > > > /* lock lru list/PageCompound, ref frozen by page_ref_freez= e */ > > > > //1st lock here > > > > lruvec =3D folio_lruvec_lock(folio); > > > > > > > > for (i =3D nr - new_nr; i >=3D new_nr; i -=3D new_nr) { > > > > __split_huge_page_tail(folio, i, lruvec, list, new_= order); > > > > /* Some pages can be beyond EOF: drop them from pag= e cache */ > > > > if (head[i].index >=3D end) { > > > > folio_put(tail); > > > > __page_cache_release > > > > //2nd lock here > > > > folio_lruvec_relock_irqsave > > > > > > Why doesn't lockdep catch this? > > It is reported by a regression test of the fix patch which aims at the > > find_get_entry livelock issue as below. I don't know the details of > > the kernel configuration. > > > > https://lore.kernel.org/linux-mm/5f989315-e380-46aa-80d1-ce8608889e5f@m= arcinwanat.pl/ > > Go away. ok, you are the boss anyway. But this series of call chain does have the risk of deadlock, right? Besides, the livelock issue which is caused by zero ref-count folio within find_get_entry is kept being reported by different users. https://lore.kernel.org/linux-mm/CALOAHbC8NM7R-pKvPW6m4fnn_8BQZuPjJrNZaEN= =3Dsg67Gp+NGQ@mail.gmail.com/