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Wed, 15 Mar 2023 11:05:56 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id LiNjEZSmEWTzXAAAMHmgww (envelope-from ); Wed, 15 Mar 2023 11:05:56 +0000 Message-ID: Date: Wed, 15 Mar 2023 12:05:55 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 4/7] mm, pagemap: remove SLOB and SLQB from comments and documentation Content-Language: en-US To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Christoph Lameter , David Rientjes , Joonsoo Kim , Pekka Enberg , Roman Gushchin , Andrew Morton , linux-mm@kvack.org, rcu@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, netdev@vger.kernel.org, linux-doc@vger.kernel.org, Lorenzo Stoakes References: <20230310103210.22372-1-vbabka@suse.cz> <20230310103210.22372-5-vbabka@suse.cz> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 46B744001F X-Rspamd-Server: rspam01 X-Stat-Signature: 1r8c4sz4pe7dgpky4kfjtq8ppx1p5u7m X-HE-Tag: 1678878358-535068 X-HE-Meta: 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 XSp64NAQ gwCiuVwxGQ2LJ/HqpRmg3rpbwSDHBoxT/8uRTdpDo5uxIIkRLC+Kj/ymDStUjkn401n0Gzw79upiLrexBj81/zZA2iEM6JEQe6AsnsDxx40El8KpbgfcLIpL+Bz9uR+9EEjOoPJb7h7Zd0W7Stsu5QfiuPA9UwP+sttJudmJJCvP4Ag17l502OblR/I5S8gj6mX8KsrzRpJfn5eK/HI7Mp4PTD3AdDGjM6tcACBa84lF4GGpL8tR8tVNVd4vU63TOCUtk+Y+UJ7916y0rKIfOX/Fw0wovuXqJg1f4 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 3/14/23 09:19, Hyeonggon Yoo wrote: > On Fri, Mar 10, 2023 at 11:32:06AM +0100, Vlastimil Babka wrote: >> SLOB has been removed and SLQB never merged, so remove their mentions >> from comments and documentation of pagemap. >> >> Signed-off-by: Vlastimil Babka >> --- >> Documentation/admin-guide/mm/pagemap.rst | 6 +++--- >> fs/proc/page.c | 5 ++--- >> 2 files changed, 5 insertions(+), 6 deletions(-) >> >> diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst >> index b5f970dc91e7..bb4aa897a773 100644 >> --- a/Documentation/admin-guide/mm/pagemap.rst >> +++ b/Documentation/admin-guide/mm/pagemap.rst >> @@ -91,9 +91,9 @@ Short descriptions to the page flags >> The page is being locked for exclusive access, e.g. by undergoing read/write >> IO. >> 7 - SLAB >> - The page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator. >> - When compound page is used, SLUB/SLQB will only set this flag on the head >> - page; SLOB will not flag it at all. >> + The page is managed by the SLAB/SLUB kernel memory allocator. >> + When compound page is used, either will only set this flag on the head >> + page.. >> 10 - BUDDY >> A free memory block managed by the buddy system allocator. >> The buddy system organizes free memory in blocks of various orders. >> diff --git a/fs/proc/page.c b/fs/proc/page.c >> index 6249c347809a..1356aeffd8dc 100644 >> --- a/fs/proc/page.c >> +++ b/fs/proc/page.c >> @@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page) >> /* >> * pseudo flags for the well known (anonymous) memory mapped pages >> * >> - * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the >> + * Note that page->_mapcount is overloaded in SLAB/SLUB, so the > > SLUB does not overload _mapcount. True, I overlooked that, thanks. >> * simple test in page_mapped() is not enough. >> */ >> if (!PageSlab(page) && page_mapped(page)) >> @@ -166,8 +166,7 @@ u64 stable_page_flags(struct page *page) >> >> /* >> * Caveats on high order pages: page->_refcount will only be set >> - * -1 on the head page; SLUB/SLQB do the same for PG_slab; >> - * SLOB won't set PG_slab at all on compound pages. >> + * -1 on the head page; SLAB/SLUB do the same for PG_slab; > > I think this comment could be just saying that PG_buddy is only set on > head page, not saying > > _refcount is set to -1 on head page (is it even correct?) It's not, that scheme is outdated. So I'll have it mention PG_buddy as you suggest, but PG_slab also needs special care as it's not set on tail pages. But I noticed the compound_head() is unnecessary as that's covered by PageSlab() which is defined as PF_NO_TAIL. So the sum of modifications to this patch: diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst index bb4aa897a773..c8f380271cad 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -93,7 +93,7 @@ Short descriptions to the page flags 7 - SLAB The page is managed by the SLAB/SLUB kernel memory allocator. When compound page is used, either will only set this flag on the head - page.. + page. 10 - BUDDY A free memory block managed by the buddy system allocator. The buddy system organizes free memory in blocks of various orders. diff --git a/fs/proc/page.c b/fs/proc/page.c index 1356aeffd8dc..195b077c0fac 100644 --- a/fs/proc/page.c +++ b/fs/proc/page.c @@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page) /* * pseudo flags for the well known (anonymous) memory mapped pages * - * Note that page->_mapcount is overloaded in SLAB/SLUB, so the + * Note that page->_mapcount is overloaded in SLAB, so the * simple test in page_mapped() is not enough. */ if (!PageSlab(page) && page_mapped(page)) @@ -165,8 +165,8 @@ u64 stable_page_flags(struct page *page) /* - * Caveats on high order pages: page->_refcount will only be set - * -1 on the head page; SLAB/SLUB do the same for PG_slab; + * Caveats on high order pages: PG_buddy and PG_slab will only be set + * on the head page. */ if (PageBuddy(page)) u |= 1 << KPF_BUDDY; @@ -184,7 +184,7 @@ u64 stable_page_flags(struct page *page) u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); u |= kpf_copy_bit(k, KPF_SLAB, PG_slab); - if (PageTail(page) && PageSlab(compound_head(page))) + if (PageTail(page) && PageSlab(page)) u |= 1 << KPF_SLAB; u |= kpf_copy_bit(k, KPF_ERROR, PG_error);