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Tue, 27 Feb 2024 13:29:12 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id LgRcGqjj3WVALwAAD6G6ig (envelope-from ); Tue, 27 Feb 2024 13:29:12 +0000 Date: Tue, 27 Feb 2024 14:29:12 +0100 From: Michal Hocko To: gregkh@linuxfoundation.org Cc: akpm@linux-foundation.org, guro@fb.com, hannes@cmpxchg.org, hughd@google.com, shakeelb@google.com, torvalds@linux-foundation.org, stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] memcg: fix use-after-free in uncharge_batch" failed to apply to 5.4-stable tree Message-ID: References: <2024022759-crave-busily-bef7@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2024022759-crave-busily-bef7@gregkh> X-Spam-Level: Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b=RulxtCmi X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.52 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; FROM_HAS_DN(0.00)[]; DWL_DNSWL_MED(-2.00)[suse.com:dkim]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; DKIM_TRACE(0.00)[suse.com:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[8]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:dkim,suse.com:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; MID_RHS_NOT_FQDN(0.50)[]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-0.51)[80.05%] X-Spam-Score: -3.52 X-Rspamd-Queue-Id: 751422248B X-Spam-Flag: NO Why is this applied to 5.4? $ git describe-ver 1a3e1f40962c v5.9-rc1~97^2~97 I do not see 1a3e1f40962c in 5.4 stable tree. What am I missing? On Tue 27-02-24 14:12:00, Greg KH wrote: [...] > Fixes: 1a3e1f40962c ("mm: memcontrol: decouple reference counting from page accounting") > Reported-by: syzbot+b305848212deec86eabe@syzkaller.appspotmail.com > Reported-by: syzbot+b5ea6fb6f139c8b9482b@syzkaller.appspotmail.com > Signed-off-by: Michal Hocko > Signed-off-by: Andrew Morton > Reviewed-by: Shakeel Butt > Acked-by: Johannes Weiner > Cc: Roman Gushchin > Cc: Hugh Dickins > Link: https://lkml.kernel.org/r/20200820090341.GC5033@dhcp22.suse.cz > Signed-off-by: Linus Torvalds > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b807952b4d43..cfa6cbad21d5 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -6774,6 +6774,9 @@ static void uncharge_batch(const struct uncharge_gather *ug) > __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_pages); > memcg_check_events(ug->memcg, ug->dummy_page); > local_irq_restore(flags); > + > + /* drop reference from uncharge_page */ > + css_put(&ug->memcg->css); > } > > static void uncharge_page(struct page *page, struct uncharge_gather *ug) > @@ -6797,6 +6800,9 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug) > uncharge_gather_clear(ug); > } > ug->memcg = page->mem_cgroup; > + > + /* pairs with css_put in uncharge_batch */ > + css_get(&ug->memcg->css); > } > > nr_pages = compound_nr(page); -- Michal Hocko SUSE Labs