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From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: linux-mm@kvack.org, akpm@linux-foundation.org, dan.j.williams@intel.com
Cc: pavel.tatashin@microsoft.com, mhocko@suse.com,
	dave.jiang@intel.com, linux-nvdimm@lists.01.org,
	linux-kernel@vger.kernel.org, dave.hansen@intel.com,
	jglisse@redhat.com, alexander.h.duyck@linux.intel.com,
	logang@deltatee.com, mingo@kernel.org,
	kirill.shutemov@linux.intel.com
Subject: [mm PATCH] memremap: Fix reference count for pgmap in devm_memremap_pages
Date: Mon, 08 Oct 2018 16:34:33 -0700	[thread overview]
Message-ID: <20181008233404.1909.37302.stgit@localhost.localdomain> (raw)
In-Reply-To: <CAPcyv4jX5WYmMYzGCBrnaqT7tqHGSVPwm7Dpi-XpuM9ns84+0w@mail.gmail.com>

In the earlier patch "mm: defer ZONE_DEVICE page initialization to the
point where we init pgmap" I had overlooked the reference count that was
being held per page on the pgmap. As a result on running the ndctl test
"create.sh" we would call into devm_memremap_pages_release and encounter
the following percpu reference count error and hang:
  WARNING: CPU: 30 PID: 0 at lib/percpu-refcount.c:155
  percpu_ref_switch_to_atomic_rcu+0xf3/0x120

This patch addresses that by performing an update for all of the device
PFNs in a single call. In my testing this seems to resolve the issue while
still allowing us to retain the improvements seen in memory initialization.

Reported-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 kernel/memremap.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 6ec81e0d7a33..9eced2cc9f94 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -218,6 +218,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
 				align_start >> PAGE_SHIFT,
 				align_size >> PAGE_SHIFT, pgmap);
+	percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
 
 	devm_add_action(dev, devm_memremap_pages_release, pgmap);
 


  parent reply	other threads:[~2018-10-08 23:34 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-25 20:18 [PATCH v5 0/4] Address issues slowing persistent memory initialization Alexander Duyck
2018-09-25 20:19 ` [PATCH v5 1/4] mm: Remove now defunct NO_BOOTMEM from depends list for deferred init Alexander Duyck
2018-09-25 21:05   ` Mike Rapoport
2018-09-25 20:20 ` [PATCH v5 2/4] mm: Provide kernel parameter to allow disabling page init poisoning Alexander Duyck
2018-09-25 20:26   ` Dave Hansen
2018-09-25 20:38     ` Alexander Duyck
2018-09-25 22:14       ` Dave Hansen
2018-09-25 22:27         ` Alexander Duyck
2018-09-26  7:38   ` Michal Hocko
2018-09-26 15:24     ` Alexander Duyck
2018-09-26 15:39       ` Michal Hocko
2018-09-26 15:41       ` Dave Hansen
2018-09-26 16:18         ` Alexander Duyck
2018-09-26 15:36     ` Dave Hansen
2018-09-26 22:36       ` Andrew Morton
2018-09-25 20:20 ` [PATCH v5 3/4] mm: Create non-atomic version of SetPageReserved for init use Alexander Duyck
2018-09-25 20:21 ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Alexander Duyck
2018-09-26  7:55   ` Michal Hocko
2018-09-26 18:25     ` Alexander Duyck
2018-09-26 18:52       ` Dan Williams
2018-09-27 11:20         ` Michal Hocko
2018-09-27 11:09       ` Michal Hocko
2018-09-27 12:25         ` Oscar Salvador
2018-09-27 13:13           ` Michal Hocko
2018-09-27 14:50             ` Oscar Salvador
2018-09-27 15:41               ` David Hildenbrand
2018-09-28  8:12             ` Oscar Salvador
2018-09-28  8:44               ` Oscar Salvador
2018-09-28 15:50                 ` Dan Williams
2018-09-27 12:32       ` Oscar Salvador
2018-10-08 21:01   ` Dan Williams
2018-10-08 21:38     ` Alexander Duyck
2018-10-08 22:00       ` Dan Williams
2018-10-08 22:07         ` Alexander Duyck
2018-10-08 22:36         ` Alexander Duyck
2018-10-08 22:59           ` Dan Williams
2018-10-08 23:34     ` Alexander Duyck [this message]
2018-10-09  0:20       ` [mm PATCH] memremap: Fix reference count for pgmap in devm_memremap_pages Dan Williams
2018-10-09 17:00   ` [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap Yi Zhang
2018-10-09 18:04     ` Dan Williams
2018-10-09 20:26       ` Alexander Duyck
2018-10-09 21:19         ` Dan Williams
2018-10-10 12:52           ` Yi Zhang
2018-10-10 15:27             ` Alexander Duyck
2018-10-11  8:17               ` Yi Zhang
2018-10-10  9:58         ` Michal Hocko
2018-10-10 16:39           ` Alexander Duyck
2018-10-10 17:24             ` Michal Hocko
2018-10-10 17:39               ` Alexander Duyck
2018-10-10 17:53                 ` Michal Hocko
2018-10-10 18:13                   ` Alexander Duyck
2018-10-10 18:52                 ` Michal Hocko
2018-10-11  8:55                   ` Michal Hocko
2018-10-11 17:38                     ` Alexander Duyck
2018-10-11 18:22                       ` Dan Williams
2018-10-17  7:52                       ` Michal Hocko
2018-10-17 15:02                         ` Alexander Duyck
2018-10-29 14:12                           ` Michal Hocko
2018-10-29 15:59                             ` Alexander Duyck
2018-10-29 16:35                               ` Michal Hocko
2018-10-29 17:01                                 ` Alexander Duyck
2018-10-29 17:24                                   ` Michal Hocko
2018-10-29 17:34                                     ` Dan Williams
2018-10-29 17:45                                       ` Michal Hocko
2018-10-29 17:42                                     ` Alexander Duyck
2018-10-29 18:18                                       ` Michal Hocko
2018-10-29 19:59                                         ` Alexander Duyck
2018-10-30  6:29                                           ` Michal Hocko
2018-10-30  6:55                                             ` Dan Williams
2018-10-30  8:17                                               ` Michal Hocko
2018-10-30 15:57                                                 ` Dan Williams
2018-10-30  8:05                                           ` Oscar Salvador
2018-10-29 15:49                           ` Dan Williams
2018-10-29 15:56                             ` Michal Hocko
2018-10-10 18:18               ` Dan Williams
2018-10-11  8:39                 ` Yi Zhang
2018-10-11 15:38                   ` Alexander Duyck

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