From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rashmica Gupta <rashmica.g@gmail.com>,
Balbir Singh <bsingharora@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Dan Williams <dan.j.williams@intel.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
Reza Arbab <arbab@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v1 09/10] mm/memory_hotplug: teach offline_pages() to not try forever
Date: Thu, 24 May 2018 16:39:53 +0200 [thread overview]
Message-ID: <20180524143953.GK20441@dhcp22.suse.cz> (raw)
In-Reply-To: <20180523151151.6730-10-david@redhat.com>
[I didn't really go through other patch but this one caught my eyes just
because of the similar request proposed yesterday]
On Wed 23-05-18 17:11:50, David Hildenbrand wrote:
[...]
> @@ -1686,6 +1686,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
> pfn = scan_movable_pages(start_pfn, end_pfn);
> if (pfn) { /* We have movable pages */
> ret = do_migrate_range(pfn, end_pfn);
> + if (ret && !retry_forever) {
> + ret = -EBUSY;
> + goto failed_removal;
> + }
> goto repeat;
> }
>
Btw. this will not work in practice. Even a single temporary pin on a page
will fail way too easily. If you really need to control this then make
it a retry counter with default -1UL.
We really do need a better error reporting from do_migrate_range and
distinguish transient from permanent failures. In general we shouldn't
even get here for pages which are not migrateable...
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-05-24 14:39 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-23 15:11 [PATCH v1 00/10] mm: online/offline 4MB chunks controlled by device driver David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 01/10] mm: introduce and use PageOffline() David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 02/10] mm/page_ext.c: support online/offline of memory < section size David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 03/10] kasan: prepare for online/offline of different start/size David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 04/10] kdump: include PAGE_OFFLINE_MAPCOUNT_VALUE in VMCOREINFO David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 05/10] mm/memory_hotplug: limit offline_pages() to sizes we can actually handle David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 06/10] mm/memory_hotplug: onlining pages can only fail due to notifiers David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 07/10] mm/memory_hotplug: print only with DEBUG_VM in online/offline_pages() David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 08/10] mm/memory_hotplug: allow to control onlining/offlining of memory by a driver David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 09/10] mm/memory_hotplug: teach offline_pages() to not try forever David Hildenbrand
2018-05-24 14:39 ` Michal Hocko [this message]
2018-05-24 20:36 ` David Hildenbrand
2018-05-23 15:11 ` [PATCH v1 10/10] mm/memory_hotplug: allow online/offline memory by a kernel module David Hildenbrand
2018-05-23 19:51 ` Christoph Hellwig
2018-05-24 5:59 ` David Hildenbrand
2018-05-24 7:53 ` [PATCH v1 00/10] mm: online/offline 4MB chunks controlled by device driver Michal Hocko
2018-05-24 8:31 ` David Hildenbrand
2018-05-24 8:56 ` Dave Young
2018-05-24 9:14 ` David Hildenbrand
2018-05-28 8:28 ` Dave Young
2018-05-28 10:03 ` David Hildenbrand
2018-05-24 9:31 ` Michal Hocko
2018-05-24 10:45 ` David Hildenbrand
2018-05-24 12:03 ` Michal Hocko
2018-05-24 14:04 ` David Hildenbrand
2018-05-24 14:22 ` Michal Hocko
2018-05-24 21:07 ` David Hildenbrand
2018-06-11 11:53 ` David Hildenbrand
2018-06-11 11:56 ` Michal Hocko
2018-06-11 12:33 ` David Hildenbrand
2018-07-16 19:48 ` David Hildenbrand
2018-07-16 20:05 ` Michal Hocko
2018-07-18 9:56 ` David Hildenbrand
2018-07-18 11:23 ` Michal Hocko
2018-07-18 13:19 ` Michal Hocko
2018-07-18 13:39 ` David Hildenbrand
2018-07-18 13:43 ` Michal Hocko
2018-07-18 13:47 ` David Hildenbrand
2018-07-18 13:56 ` Michal Hocko
2018-05-25 15:08 ` David Hildenbrand
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