LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Michal Hocko <mhocko@suse.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Muchun Song <songmuchun@bytedance.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 3/7] mm,hugetlb: Clear HPageFreed outside of the lock
Date: Wed, 14 Apr 2021 08:04:21 +0200
Message-ID: <YHaF5efHcJJ71UP9@dhcp22.suse.cz> (raw)
In-Reply-To: <b8f36340-df56-1180-2a14-7b20cc1a0cda@oracle.com>

On Tue 13-04-21 14:19:03, Mike Kravetz wrote:
> On 4/13/21 6:23 AM, Michal Hocko wrote:
> > On Tue 13-04-21 12:47:43, Oscar Salvador wrote:
[...]
> > Or do we need it for giga pages which are not allocated by the page
> > allocator? If yes then moving it to prep_compound_gigantic_page would be
> > better.
> 
> I am pretty sure dynamically allocated giga pages have page->Private
> cleared as well.  It is not obvious, but the alloc_contig_range code
> used to put together giga pages will end up calling isolate_freepages_range
> that will call split_map_pages and then post_alloc_hook for each MAX_ORDER
> block.

Thanks for saving me from crawling that code.

> As mentioned, this is not obvious and I would hate to rely on this
> behavior not changing.

Thinking about it some more, having some (page granularity) allocator
not clearing page private would be a serious problem for anybody relying
on its state. So I am not sure this can change.
 
> > So should we just drop it here?
> 
> The only place where page->private may not be initialized is when we do
> allocations at boot time from memblock.  In this case, we will add the
> pages to the free list via put_page/free_huge_page so the appropriate
> flags will be cleared before anyone notices.

Pages allocated by the bootmem should be pre initialized from the boot,
no?

> I'm wondering if we should just do a set_page_private(page, 0) here in
> prep_new_huge_page since we now use that field for flags.  Or, is that
> overkill?

I would rather not duplicate the work done by underlying allocators. I
do not think other users of the allocator want to do the same so why
should hugetlb be any different.
-- 
Michal Hocko
SUSE Labs

  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 10:47 [PATCH v7 0/7] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 1/7] mm,page_alloc: Bail out earlier on -ENOMEM in alloc_contig_migrate_range Oscar Salvador
2021-04-13 17:00   ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 2/7] mm,compaction: Let isolate_migratepages_{range,block} return error codes Oscar Salvador
2021-04-13 17:52   ` Mike Kravetz
2021-04-14 11:54   ` David Hildenbrand
2021-04-15  8:42     ` Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 3/7] mm,hugetlb: Clear HPageFreed outside of the lock Oscar Salvador
2021-04-13 13:23   ` Michal Hocko
2021-04-13 21:19     ` Mike Kravetz
2021-04-14  6:04       ` Michal Hocko [this message]
2021-04-14  7:41         ` Oscar Salvador
2021-04-14  8:28           ` Michal Hocko
2021-04-14 10:01             ` Oscar Salvador
2021-04-14 10:03               ` Oscar Salvador
2021-04-14 10:32               ` Michal Hocko
2021-04-14 10:49                 ` Oscar Salvador
2021-04-14 11:09                   ` Michal Hocko
2021-04-14 12:02                     ` David Hildenbrand
2021-04-14 16:45                   ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 4/7] mm,hugetlb: Split prep_new_huge_page functionality Oscar Salvador
2021-04-13 13:24   ` Michal Hocko
2021-04-13 13:26     ` Michal Hocko
2021-04-13 21:33   ` Mike Kravetz
2021-04-14  4:59     ` Oscar Salvador
2021-04-14 12:15       ` David Hildenbrand
2021-04-14 17:03       ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 5/7] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-04-13 13:40   ` Michal Hocko
2021-04-15  8:29     ` Oscar Salvador
2021-04-13 22:29   ` Mike Kravetz
2021-04-14  4:54     ` Oscar Salvador
2021-04-14 12:26   ` David Hildenbrand
2021-04-15  8:28     ` Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 6/7] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-04-13 22:48   ` Mike Kravetz
2021-04-14  4:52     ` Oscar Salvador
2021-04-14 17:07       ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 7/7] mm,page_alloc: Drop unnecessary checks from pfn_range_valid_contig Oscar Salvador
2021-04-13 22:53   ` Mike Kravetz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YHaF5efHcJJ71UP9@dhcp22.suse.cz \
    --to=mhocko@suse.com \
    --cc=akpm@linux-foundation.org \
    --cc=david@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mike.kravetz@oracle.com \
    --cc=osalvador@suse.de \
    --cc=songmuchun@bytedance.com \
    --cc=vbabka@suse.cz \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git
	git clone --mirror https://lore.kernel.org/lkml/10 lkml/git/10.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git