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Wed, 09 Jun 2021 11:39:35 +0000 From: Vlastimil Babka To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra , Jann Horn , Vlastimil Babka Subject: [RFC v2 21/34] mm, slub: call deactivate_slab() without disabling irqs Date: Wed, 9 Jun 2021 13:38:50 +0200 Message-Id: <20210609113903.1421-22-vbabka@suse.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210609113903.1421-1-vbabka@suse.cz> References: <20210609113903.1421-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="xNml2b/x"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=aRLQO7bh; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="xNml2b/x"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=aRLQO7bh; spf=pass (imf05.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none X-Stat-Signature: wyd3ew8ufp7daa4sred6mwhstt3fgory X-Rspamd-Queue-Id: 83A47E000265 X-Rspamd-Server: rspam06 X-HE-Tag: 1623238771-260767 Content-Transfer-Encoding: quoted-printable 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: The function is now safe to be called with irqs enabled, so move the call= s outside of irq disabled sections. When called from ___slab_alloc() -> flush_slab() we have irqs disabled, s= o to reenable them before deactivate_slab() we need to open-code flush_slab() = in ___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fiel= ds. But that means a IRQ handler meanwhile might have assigned a new page to kmem_cache_cpu.page so we have to retry the whole check. The remaining callers of flush_slab() are the IPI handler which has disab= led irqs anyway, and slub_cpu_dead() which will be dealt with in the followin= g patch. Signed-off-by: Vlastimil Babka --- mm/slub.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index bba18146def6..a99a254f2410 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2706,8 +2706,8 @@ static void *___slab_alloc(struct kmem_cache *s, gf= p_t gfpflags, int node, freelist =3D c->freelist; c->page =3D NULL; c->freelist =3D NULL; - deactivate_slab(s, page, freelist); local_irq_restore(flags); + deactivate_slab(s, page, freelist); =20 new_slab: =20 @@ -2775,18 +2775,32 @@ static void *___slab_alloc(struct kmem_cache *s, = gfp_t gfpflags, int node, */ goto return_single; =20 +retry_load_page: + local_irq_save(flags); - if (unlikely(c->page)) - flush_slab(s, c); + if (unlikely(c->page)) { + void *flush_freelist =3D c->freelist; + struct page *flush_page =3D c->page; + + c->page =3D NULL; + c->freelist =3D NULL; + c->tid =3D next_tid(c->tid); + + local_irq_restore(flags); + + deactivate_slab(s, flush_page, flush_freelist); + + stat(s, CPUSLAB_FLUSH); + + goto retry_load_page; + } c->page =3D page; =20 goto load_freelist; =20 return_single: =20 - local_irq_save(flags); deactivate_slab(s, page, get_freepointer(s, freelist)); - local_irq_restore(flags); return freelist; } =20 --=20 2.31.1