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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id c11-20020a05620a134b00b006809a92a94fsm11678306qkl.79.2022.03.30.22.14.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 22:14:33 -0700 (PDT) Date: Wed, 30 Mar 2022 22:14:22 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.anvils To: Matthew Wilcox cc: Hugh Dickins , Johannes Weiner , Muchun Song , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: WARNING: mm/workingset.c:567 shadow_lru_isolate In-Reply-To: Message-ID: <20f5a12f-416b-458b-80f1-e4c13cd1ec64@google.com> References: <55db706b-9bce-b820-7d88-6392374cd4fc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=AAlCwujb; spf=pass (imf01.hostedemail.com: domain of hughd@google.com designates 209.85.160.181 as permitted sender) smtp.mailfrom=hughd@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4CF8D4000B X-Stat-Signature: iuw85o17ze74b7x1zwdhnoziehzdz8m9 X-HE-Tag: 1648703675-9135 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: On Wed, 30 Mar 2022, Matthew Wilcox wrote: > On Mon, Mar 28, 2022 at 09:24:00PM -0700, Hugh Dickins wrote: > > I'm not familiar with workingset.c, I'll make no guesses, over to you! > > I haven't been able to reproduce it, but I applied Feynman's Problem > Solving Algorithm, and I think this will do the trick: Excellent! Yes, this fixes it - thanks. Hugh > > diff --git a/lib/xarray.c b/lib/xarray.c > index b95e92598b9c..d3b168f619b1 100644 > --- a/lib/xarray.c > +++ b/lib/xarray.c > @@ -1079,6 +1079,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order) > xa_mk_node(child)); > if (xa_is_value(curr)) > values--; > + xas_update(xas, child); > } else { > unsigned int canon = offset - xas->xa_sibs; > > @@ -1093,6 +1094,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order) > } while (offset-- > xas->xa_offset); > > node->nr_values += values; > + xas_update(xas, node); > } > EXPORT_SYMBOL_GPL(xas_split); > #endif > > (the key insight is that the update function should have removed the > node from the list; the WARN_ON really means "this node should not be on > the list", so there's somewhere that we're forgetting to call > xas_update(), or somewhere that we're forgetting to call > mapping_set_update(). I didn't find any of the latter, but I did find > one of the former)