From: Michal Hocko <mhocko@kernel.org>
To: Oscar Salvador <osalvador@suse.de>
Cc: n-horiguchi@ah.jp.nec.com, mike.kravetz@oracle.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 11/16] mm,hwpoison: Rework soft offline for in-use pages
Date: Tue, 22 Oct 2019 10:30:02 +0200 [thread overview]
Message-ID: <20191022083002.GE9379@dhcp22.suse.cz> (raw)
In-Reply-To: <20191022075626.GB19060@linux>
On Tue 22-10-19 09:56:27, Oscar Salvador wrote:
> On Mon, Oct 21, 2019 at 04:06:19PM +0200, Michal Hocko wrote:
> > On Mon 21-10-19 15:48:48, Oscar Salvador wrote:
> > > We can only perform actions on LRU/Movable pages or hugetlb pages.
> >
> > What would prevent other pages mapped via page tables to be handled as
> > well?
>
> What kind of pages?
Any pages mapped to the userspace. E.g. driver memory which is not on
LRU.
> I mean, I guess it could be done, it was just not implemented, and I
> did not want to add more "features" as my main goal was to re-work
> the interface to be more deterministic.
Fair enough. One step at the time sounds definitely good
> > > 1) we would need to hook in enqueue_hugetlb_page so the page is not enqueued
> > > into hugetlb freelists
> > > 2) when trying to free a hugetlb page, we would need to do as we do for gigantic
> > > pages now, and that is breaking down the pages into order-0 pages and release
> > > them to the buddy (so the check in free_papges_prepare would skip the
> > > hwpoison page).
> > > Trying to handle a higher-order hwpoison page in free_pages_prepare is
> > > a bit complicated.
> >
> > I am not sure I see the problem. If you dissolve the hugetlb page then
> > there is no hugetlb page anymore and so you make it a regular high-order
> > page.
>
> Yes, but the problem comes when trying to work with a hwpoison high-order page
> in free_pages_prepare, it gets more complicated, and when I weigthed
> code vs benefits, I was not really sure to go down that road.
>
> If we get a hwpoison high-order page in free_pages_prepare, we need to
> break it down to smaller pages, so we can skip the "bad" to not be sent
> into buddy allocator.
But we have destructors for compound pages. Can we do the heavy lifting
there?
> > If the page is free then it shouldn't pin the memcg or any other state.
>
> Well, it is not really free, as it is not usable, is it?
Sorry I meant to say the page is free from the memcg POV - aka no task
from the memcg is holding a reference to it. The page is not usable for
anybody, that is true but no particular memcg should pay a price for
that. This would mean that random memcgs would end up pinned for ever
without a good reason.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-10-22 8:30 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 14:21 [RFC PATCH v2 00/16] Hwpoison rework {hard,soft}-offline Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 01/16] mm,hwpoison: cleanup unused PageHuge() check Oscar Salvador
2019-10-18 11:48 ` Michal Hocko
2019-10-21 7:00 ` Naoya Horiguchi
2019-10-21 12:16 ` Michal Hocko
2019-11-12 12:22 ` Aneesh Kumar K.V
2019-11-13 6:02 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 02/16] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED Oscar Salvador
2019-10-18 11:52 ` Michal Hocko
2019-10-21 7:02 ` Naoya Horiguchi
2019-10-21 12:20 ` Michal Hocko
2019-10-17 14:21 ` [RFC PATCH v2 03/16] mm,madvise: Refactor madvise_inject_error Oscar Salvador
2019-10-21 7:03 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 04/16] mm,hwpoison-inject: don't pin for hwpoison_filter Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 05/16] mm,hwpoison: Un-export get_hwpoison_page and make it static Oscar Salvador
2019-10-21 7:03 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 06/16] mm,hwpoison: Kill put_hwpoison_page Oscar Salvador
2019-10-21 7:04 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 07/16] mm,hwpoison: remove MF_COUNT_INCREASED Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 08/16] mm,hwpoison: remove flag argument from soft offline functions Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 09/16] mm,hwpoison: Unify THP handling for hard and soft offline Oscar Salvador
2019-10-21 7:04 ` Naoya Horiguchi
2019-10-21 9:51 ` [PATCH 17/16] mm,hwpoison: introduce MF_MSG_UNSPLIT_THP Naoya Horiguchi
2019-10-22 8:00 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 10/16] mm,hwpoison: Rework soft offline for free pages Oscar Salvador
2019-10-18 12:06 ` Michal Hocko
2019-10-21 12:58 ` Oscar Salvador
2019-10-21 15:41 ` Michal Hocko
2019-10-22 7:46 ` Oscar Salvador
2019-10-22 8:26 ` Michal Hocko
2019-10-22 8:35 ` Oscar Salvador
2019-10-22 9:22 ` Michal Hocko
2019-10-22 9:58 ` Oscar Salvador
2019-10-22 10:24 ` Michal Hocko
2019-10-22 10:33 ` Oscar Salvador
2019-10-23 2:15 ` Naoya Horiguchi
2019-10-23 2:01 ` Naoya Horiguchi
2019-10-21 7:45 ` Naoya Horiguchi
2019-10-22 8:00 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 11/16] mm,hwpoison: Rework soft offline for in-use pages Oscar Salvador
2019-10-18 12:39 ` Michal Hocko
2019-10-21 13:48 ` Oscar Salvador
2019-10-21 14:06 ` Michal Hocko
2019-10-22 7:56 ` Oscar Salvador
2019-10-22 8:30 ` Michal Hocko [this message]
2019-10-22 9:40 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 12/16] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 13/16] mm,hwpoison: Take pages off the buddy when hard-offlining Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 14/16] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline Oscar Salvador
2019-10-21 9:20 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 15/16] mm/hwpoison-inject: Rip off duplicated checks Oscar Salvador
2019-10-21 9:40 ` David Hildenbrand
2019-10-22 7:57 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 16/16] mm, soft-offline: convert parameter to pfn Oscar Salvador
2019-10-18 8:15 ` David Hildenbrand
2020-06-11 16:43 ` [RFC PATCH v2 00/16] Hwpoison rework {hard,soft}-offline Dmitry Yakunin
2020-06-15 6:19 ` HORIGUCHI NAOYA(堀口 直也)
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