lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 11 Aug 2020 09:50:10 +0800 From: Abel Wu <wuyun.wu@...wei.com> To: David Rientjes <rientjes@...gle.com> CC: Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>, Joonsoo Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>, <liu.xiang6@....com.cn>, "open list:SLAB ALLOCATOR" <linux-mm@...ck.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] mm/slub: remove useless kmem_cache_debug On 2020/8/11 9:29, Abel Wu wrote: > > > On 2020/8/11 3:44, David Rientjes wrote: >> On Mon, 10 Aug 2020, wuyun.wu@...wei.com wrote: >> >>> From: Abel Wu <wuyun.wu@...wei.com> >>> >>> The commit below is incomplete, as it didn't handle the add_full() part. >>> commit a4d3f8916c65 ("slub: remove useless kmem_cache_debug() before remove_full()") >>> >>> Signed-off-by: Abel Wu <wuyun.wu@...wei.com> >>> --- >>> mm/slub.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/mm/slub.c b/mm/slub.c >>> index fe81773..0b021b7 100644 >>> --- a/mm/slub.c >>> +++ b/mm/slub.c >>> @@ -2182,7 +2182,8 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, >>> } >>> } else { >>> m = M_FULL; >>> - if (kmem_cache_debug(s) && !lock) { >>> +#ifdef CONFIG_SLUB_DEBUG >>> + if (!lock) { >>> lock = 1; >>> /* >>> * This also ensures that the scanning of full >>> @@ -2191,6 +2192,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, >>> */ >>> spin_lock(&n->list_lock); >>> } >>> +#endif >>> } >>> >>> if (l != m) { >> >> This should be functionally safe, I'm wonder if it would make sense to >> only check for SLAB_STORE_USER here instead of kmem_cache_debug(), >> however, since that should be the only context in which we need the >> list_lock for add_full()? It seems more explicit. >> . >> > Yes, checking for SLAB_STORE_USER here can also get rid of noising macros. > I will resend the patch later. > > Thanks, > Abel > . > Wait... It still needs CONFIG_SLUB_DEBUG to wrap around, but can avoid locking overhead when SLAB_STORE_USER is not set (as what you said). I will keep the CONFIG_SLUB_DEBUG in my new patch.
Powered by blists - more mailing lists