linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Qian Cai <cai@lca.pw>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Joonsoo Kim <js1304@gmail.com>,
	Shakeel Butt <shakeelb@google.com>,
	Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@suse.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Roman Gushchin <guro@fb.com>, Linux-MM <linux-mm@kvack.org>,
	cgroups@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	kernel-team@fb.com, Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 12/19] mm: memcontrol: convert anon and file-thp to new mem_cgroup_charge() API
Date: Tue, 12 May 2020 19:58:14 -0400	[thread overview]
Message-ID: <25270BAD-CB7E-4E92-96BA-740690744DBA@lca.pw> (raw)
In-Reply-To: <20200512215813.GA487759@cmpxchg.org>



> On May 12, 2020, at 5:58 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
> 
> On Tue, May 12, 2020 at 10:38:54AM -0400, Qian Cai wrote:
>>> On May 8, 2020, at 2:30 PM, Johannes Weiner <hannes@cmpxchg.org> wrote:
>>> 
>>> With the page->mapping requirement gone from memcg, we can charge anon
>>> and file-thp pages in one single step, right after they're allocated.
>>> 
>>> This removes two out of three API calls - especially the tricky commit
>>> step that needed to happen at just the right time between when the
>>> page is "set up" and when it's "published" - somewhat vague and fluid
>>> concepts that varied by page type. All we need is a freshly allocated
>>> page and a memcg context to charge.
>>> 
>>> v2: prevent double charges on pre-allocated hugepages in khugepaged
>>> 
>>> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
>>> Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>>> ---
>>> include/linux/mm.h      |  4 +---
>>> kernel/events/uprobes.c | 11 +++--------
>>> mm/filemap.c            |  2 +-
>>> mm/huge_memory.c        |  9 +++------
>>> mm/khugepaged.c         | 35 ++++++++++-------------------------
>>> mm/memory.c             | 36 ++++++++++--------------------------
>>> mm/migrate.c            |  5 +----
>>> mm/swapfile.c           |  6 +-----
>>> mm/userfaultfd.c        |  5 +----
>>> 9 files changed, 31 insertions(+), 82 deletions(-)
>> []
>>> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
>>> 
>>> @@ -1198,10 +1193,11 @@ static void collapse_huge_page(struct mm_struct *mm,
>>> out_up_write:
>>> 	up_write(&mm->mmap_sem);
>>> out_nolock:
>>> +	if (*hpage)
>>> +		mem_cgroup_uncharge(*hpage);
>>> 	trace_mm_collapse_huge_page(mm, isolated, result);
>>> 	return;
>>> out:
>>> -	mem_cgroup_cancel_charge(new_page, memcg);
>>> 	goto out_up_write;
>>> }
>> []
>> 
>> Some memory pressure will crash this new code. It looks like somewhat racy.
>> 
>> if (!page->mem_cgroup)
>> 
>> where page == NULL in mem_cgroup_uncharge().
> 
> Thanks for the report, sorry about the inconvenience.
> 
> Hm, the page is exclusive at this point, nobody else should be
> touching it. After all, khugepaged might reuse the preallocated page
> for another pmd if this one fails to collapse.
> 
> Looking at the code, I think it's page itself that's garbage, not
> page->mem_cgroup changing. If you have CONFIG_NUMA and the allocation
> fails, *hpage could contain an ERR_PTR instead of being NULL.
> 
> I think we need the following fixlet:

Yes, I have NUMA here.

Stephen, can you pick this up for first before Andrew has a chance to push out the next mmotm hopefully contain this fix?

https://lore.kernel.org/lkml/20200512215813.GA487759@cmpxchg.org/

> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index f2e0a5e5cfbb..f6161e17da26 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1193,7 +1193,7 @@ static void collapse_huge_page(struct mm_struct *mm,
> out_up_write:
> 	up_write(&mm->mmap_sem);
> out_nolock:
> -	if (*hpage)
> +	if (!IS_ERR_OR_NULL(*hpage))
> 		mem_cgroup_uncharge(*hpage);
> 	trace_mm_collapse_huge_page(mm, isolated, result);
> 	return;
> @@ -1928,7 +1928,7 @@ static void collapse_file(struct mm_struct *mm,
> 	unlock_page(new_page);
> out:
> 	VM_BUG_ON(!list_empty(&pagelist));
> -	if (*hpage)
> +	if (!IS_ERR_OR_NULL(*hpage))
> 		mem_cgroup_uncharge(*hpage);
> 	/* TODO: tracepoints */
> }



  reply	other threads:[~2020-05-12 23:58 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08 18:30 [PATCH 00/19 V2] mm: memcontrol: charge swapin pages on instantiation Johannes Weiner
2020-05-08 18:30 ` [PATCH 01/19] mm: fix NUMA node file count error in replace_page_cache() Johannes Weiner
2020-05-18 11:18   ` Balbir Singh
2020-05-08 18:30 ` [PATCH 02/19] mm: memcontrol: fix stat-corrupting race in charge moving Johannes Weiner
2020-05-08 18:30 ` [PATCH 03/19] mm: memcontrol: drop @compound parameter from memcg charging API Johannes Weiner
2020-05-08 18:30 ` [PATCH 04/19] mm: memcontrol: move out cgroup swaprate throttling Johannes Weiner
2020-05-08 18:30 ` [PATCH 05/19] mm: memcontrol: convert page cache to a new mem_cgroup_charge() API Johannes Weiner
2020-06-10 16:09   ` Michal Hocko
2020-05-08 18:30 ` [PATCH 06/19] mm: memcontrol: prepare uncharging for removal of private page type counters Johannes Weiner
2020-05-08 18:30 ` [PATCH 07/19] mm: memcontrol: prepare move_account " Johannes Weiner
2020-05-08 18:30 ` [PATCH 08/19] mm: memcontrol: prepare cgroup vmstat infrastructure for native anon counters Johannes Weiner
2020-05-08 18:30 ` [PATCH 09/19] mm: memcontrol: switch to native NR_FILE_PAGES and NR_SHMEM counters Johannes Weiner
2020-06-10 16:42   ` Michal Hocko
2020-05-08 18:30 ` [PATCH 10/19] mm: memcontrol: switch to native NR_ANON_MAPPED counter Johannes Weiner
2020-05-08 18:30 ` [PATCH 11/19] mm: memcontrol: switch to native NR_ANON_THPS counter Johannes Weiner
2020-05-08 18:30 ` [PATCH 12/19] mm: memcontrol: convert anon and file-thp to new mem_cgroup_charge() API Johannes Weiner
2020-05-12 14:38   ` Qian Cai
2020-05-12 17:11     ` Qian Cai
2020-05-12 21:58     ` Johannes Weiner
2020-05-12 23:58       ` Qian Cai [this message]
2020-05-08 18:31 ` [PATCH 13/19] mm: memcontrol: drop unused try/commit/cancel charge API Johannes Weiner
2020-06-22 17:06   ` Ben Widawsky
2020-05-08 18:31 ` [PATCH 14/19] mm: memcontrol: prepare swap controller setup for integration Johannes Weiner
2020-05-08 18:31 ` [PATCH 15/19] mm: memcontrol: make swap tracking an integral part of memory control Johannes Weiner
2020-05-08 18:31 ` [PATCH 16/19] mm: memcontrol: charge swapin pages on instantiation Johannes Weiner
2020-06-11  9:35   ` Michal Hocko
2020-06-17  8:49     ` [PATCH for 5.8] mm: do_swap_page fix up the error code instantiation Michal Hocko
2020-06-17  9:02       ` Michal Hocko
2020-06-17 13:34         ` Johannes Weiner
2020-05-08 18:31 ` [PATCH 17/19] mm: memcontrol: document the new swap control behavior Johannes Weiner
2020-05-08 18:31 ` [PATCH 18/19] mm: memcontrol: delete unused lrucare handling Johannes Weiner
2020-05-08 18:31 ` [PATCH 19/19] mm: memcontrol: update page->mem_cgroup stability rules Johannes Weiner
2020-06-11  9:40   ` Michal Hocko
2020-05-13 11:30 ` [PATCH 00/19 V2] mm: memcontrol: charge swapin pages on instantiation Balbir Singh
2020-05-13 12:35   ` Johannes Weiner
2020-05-14 11:04     ` Balbir Singh

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=25270BAD-CB7E-4E92-96BA-740690744DBA@lca.pw \
    --to=cai@lca.pw \
    --cc=akpm@linux-foundation.org \
    --cc=alex.shi@linux.alibaba.com \
    --cc=cgroups@vger.kernel.org \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=hughd@google.com \
    --cc=js1304@gmail.com \
    --cc=kernel-team@fb.com \
    --cc=kirill@shutemov.name \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@suse.com \
    --cc=sfr@canb.auug.org.au \
    --cc=shakeelb@google.com \
    --subject='Re: [PATCH 12/19] mm: memcontrol: convert anon and file-thp to new mem_cgroup_charge() API' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).