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Wed, 22 Nov 2023 09:37:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 9qsoEuTLXWWRewAAMHmgww (envelope-from ); Wed, 22 Nov 2023 09:37:40 +0000 Message-ID: <83ff4b9e-94f1-8b35-1233-3dd414ea4dfe@suse.cz> Date: Wed, 22 Nov 2023 10:37:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v5 6/9] slub: Delay freezing of partial slabs Content-Language: en-US To: Mark Brown , chengming.zhou@linux.dev Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chengming Zhou , Matthew Wilcox References: <20231102032330.1036151-1-chengming.zhou@linux.dev> <20231102032330.1036151-7-chengming.zhou@linux.dev> <4f3bc1bd-ea87-465d-b58a-0ed57b15187b@sirena.org.uk> From: Vlastimil Babka In-Reply-To: <4f3bc1bd-ea87-465d-b58a-0ed57b15187b@sirena.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [0.40 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TAGGED_RCPT(0.00)[]; MIME_GOOD(-0.10)[text/plain]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; BAYES_HAM(-3.00)[100.00%]; RCPT_COUNT_TWELVE(0.00)[13]; NEURAL_SPAM_SHORT(3.00)[1.000]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_CC(0.00)[linux.com,kernel.org,google.com,lge.com,linux-foundation.org,linux.dev,gmail.com,kvack.org,vger.kernel.org,bytedance.com,infradead.org]; RCVD_COUNT_TWO(0.00)[2]; SUSPICIOUS_RECIPS(1.50)[] Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/23 19:49, Mark Brown wrote: > On Thu, Nov 02, 2023 at 03:23:27AM +0000, chengming.zhou@linux.dev wrote: >> From: Chengming Zhou >> >> Now we will freeze slabs when moving them out of node partial list to >> cpu partial list, this method needs two cmpxchg_double operations: >> >> 1. freeze slab (acquire_slab()) under the node list_lock >> 2. get_freelist() when pick used in ___slab_alloc() > > Recently -next has been failing to boot on a Raspberry Pi 3 with an arm > multi_v7_defconfig and a NFS rootfs, a bisect appears to point to this > patch (in -next as c8d312e039030edab25836a326bcaeb2a3d4db14) as having > introduced the issue. I've included the full bisect log below. > > When we see problems we see RCU stalls while logging in, for example: Can you try this, please? ----8<---- >From 000030c1ff055ef6a2ca624d0142f08f3ef19d51 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Wed, 22 Nov 2023 10:32:41 +0100 Subject: [PATCH] mm/slub: try to fix hangs without cmpxchg64/128 If we don't have cmpxchg64/128 and resort to slab_lock()/slab_unlock() which uses PG_locked, we can get RMW with the newly introduced slab_set/clear_node_partial() operation that modify PG_workingset so all the operations have to be atomic now. Signed-off-by: Vlastimil Babka --- mm/slub.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index bcb5b2c4e213..f2cdb81ab02e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -522,7 +522,7 @@ static __always_inline void slab_unlock(struct slab *slab) struct page *page = slab_page(slab); VM_BUG_ON_PAGE(PageTail(page), page); - __bit_spin_unlock(PG_locked, &page->flags); + bit_spin_unlock(PG_locked, &page->flags); } static inline bool @@ -2127,12 +2127,12 @@ static inline bool slab_test_node_partial(const struct slab *slab) static inline void slab_set_node_partial(struct slab *slab) { - __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); + set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); } static inline void slab_clear_node_partial(struct slab *slab) { - __clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); + clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); } /* -- 2.42.1