From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Qian Cai <cai@lca.pw>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>,
Oscar Salvador <osalvador@suse.de>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Rapoport <rppt@linux.ibm.com>,
Dan Williams <dan.j.williams@intel.com>,
Pavel Tatashin <pavel.tatashin@microsoft.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()
Date: Thu, 3 Oct 2019 17:32:02 +0530 [thread overview]
Message-ID: <49fa7dea-00ac-155f-e7b7-eeca206556b5@arm.com> (raw)
In-Reply-To: <983E7EA4-A022-448C-B11D-8C10441A2E07@lca.pw>
On 10/03/2019 05:20 PM, Qian Cai wrote:
>
>
>> On Oct 3, 2019, at 7:31 AM, Anshuman Khandual <Anshuman.Khandual@arm.com> wrote:
>>
>> Ohh, never meant that the 'Reserved' bit is anything special here but it
>> is a reason to make a page unmovable unlike many other flags.
>
> But dump_page() is used everywhere, and it is better to reserve “reason” to indicate something more important rather than duplicating the page flags.
>
> Especially, it is trivial enough right now for developers look in the page flags dumping from has_unmovable_pages(), and figure out the exact branching in the code.
>
Will something like this be better ? hugepage_migration_supported() has got
uncertainty depending on platform and huge page size.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 15c2050c629b..8dbc86696515 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8175,7 +8175,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
unsigned long found;
unsigned long iter = 0;
unsigned long pfn = page_to_pfn(page);
- const char *reason = "unmovable page";
+ const char *reason;
/*
* TODO we could make this much more efficient by not checking every
@@ -8194,7 +8194,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
if (is_migrate_cma(migratetype))
return false;
- reason = "CMA page";
+ reason = "Unmovable CMA page";
goto unmovable;
}
@@ -8206,8 +8206,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
page = pfn_to_page(check);
- if (PageReserved(page))
+ if (PageReserved(page)) {
+ reason = "Unmovable reserved page";
goto unmovable;
+ }
/*
* If the zone is movable and we have ruled out all reserved
@@ -8226,8 +8228,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
struct page *head = compound_head(page);
unsigned int skip_pages;
- if (!hugepage_migration_supported(page_hstate(head)))
+ if (!hugepage_migration_supported(page_hstate(head))) {
+ reason = "Unmovable HugeTLB page";
goto unmovable;
+ }
skip_pages = compound_nr(head) - (page - head);
iter += skip_pages - 1;
@@ -8271,8 +8275,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
* is set to both of a memory hole page and a _used_ kernel
* page at boot.
*/
- if (found > count)
+ if (found > count) {
+ reason = "Unmovable non-LRU page";
goto unmovable;
+ }
}
return false;
unmovable:
next prev parent reply other threads:[~2019-10-03 12:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-03 8:10 [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages() Anshuman Khandual
2019-10-03 9:05 ` Qian Cai
2019-10-03 9:32 ` Anshuman Khandual
2019-10-03 9:53 ` Anshuman Khandual
2019-10-03 11:19 ` Qian Cai
2019-10-03 11:32 ` Anshuman Khandual
2019-10-03 11:50 ` Qian Cai
2019-10-03 12:02 ` Anshuman Khandual [this message]
2019-10-03 12:14 ` Qian Cai
2019-10-04 8:25 ` David Hildenbrand
2020-01-14 8:19 ` Anshuman Khandual
2020-01-14 8:30 ` David Hildenbrand
2020-01-14 9:10 ` Michal Hocko
2020-01-14 10:23 ` Vlastimil Babka
2020-01-14 11:03 ` Anshuman Khandual
2020-01-14 11:32 ` Michal Hocko
2020-01-14 12:04 ` [PATCH] mm, debug: always print flags in dump_page() Vlastimil Babka
2020-01-14 13:35 ` Michal Hocko
2020-01-14 18:22 ` [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages() Ralph Campbell
2019-10-04 10:58 ` Michal Hocko
2019-10-04 11:44 ` Anshuman Khandual
2019-10-04 12:56 ` Qian Cai
2019-10-04 13:07 ` Michal Hocko
2019-10-04 13:30 ` Qian Cai
2019-10-04 13:38 ` Michal Hocko
2019-10-04 13:56 ` Qian Cai
2019-10-04 14:41 ` Michal Hocko
2019-10-05 21:22 ` Andrew Morton
2019-10-05 22:38 ` Qian Cai
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=49fa7dea-00ac-155f-e7b7-eeca206556b5@arm.com \
--to=anshuman.khandual@arm.com \
--cc=akpm@linux-foundation.org \
--cc=cai@lca.pw \
--cc=dan.j.williams@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@suse.com \
--cc=osalvador@suse.de \
--cc=pavel.tatashin@microsoft.com \
--cc=rppt@linux.ibm.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).