From: "Jérôme Glisse" <jglisse@redhat.com>
To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Cc: "John Hubbard" <jhubbard@nvidia.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>,
"David Nellans" <dnellans@nvidia.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Ross Zwisler" <ross.zwisler@linux.intel.com>
Subject: [HMM 02/16] mm/put_page: move ZONE_DEVICE page reference decrement v2
Date: Wed, 5 Apr 2017 16:40:12 -0400 [thread overview]
Message-ID: <20170405204026.3940-3-jglisse@redhat.com> (raw)
In-Reply-To: <20170405204026.3940-1-jglisse@redhat.com>
Move page reference decrement of ZONE_DEVICE from put_page()
to put_zone_device_page() this does not affect non ZONE_DEVICE
page.
Doing this allow to catch when a ZONE_DEVICE page refcount reach
1 which means the device is no longer reference by any one (unlike
page from other zone, ZONE_DEVICE page refcount never reach 0).
This patch is just a preparatory patch for HMM.
Changes since v1:
- commit message
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
---
include/linux/mm.h | 14 +++++++++++---
kernel/memremap.c | 6 ++++++
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0860a2b..92db0fb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -813,11 +813,19 @@ static inline void put_page(struct page *page)
{
page = compound_head(page);
+ /*
+ * ZONE_DEVICE pages should never have their refcount reach 0 (this
+ * would be a bug), so call page_ref_dec() in put_zone_device_page()
+ * to decrement page refcount and skip __put_page() here, as this
+ * would worsen things if a ZONE_DEVICE had a refcount bug.
+ */
+ if (unlikely(is_zone_device_page(page))) {
+ put_zone_device_page(page);
+ return;
+ }
+
if (put_page_testzero(page))
__put_page(page);
-
- if (unlikely(is_zone_device_page(page)))
- put_zone_device_page(page);
}
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 6b4505d..0228a01 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -190,6 +190,12 @@ EXPORT_SYMBOL(get_zone_device_page);
void put_zone_device_page(struct page *page)
{
+ /*
+ * ZONE_DEVICE page refcount should never reach 0 and never be freed
+ * to kernel memory allocator.
+ */
+ page_ref_dec(page);
+
put_dev_pagemap(page->pgmap);
}
EXPORT_SYMBOL(put_zone_device_page);
--
2.9.3
next prev parent reply other threads:[~2017-04-05 20:40 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-05 20:40 [HMM 00/16] HMM (Heterogeneous Memory Management) v19 Jérôme Glisse
2017-04-05 20:40 ` [HMM 01/16] mm/memory/hotplug: add memory type parameter to arch_add/remove_memory Jérôme Glisse
2017-04-06 9:45 ` Anshuman Khandual
2017-04-06 13:58 ` Jerome Glisse
2017-04-07 12:13 ` Michal Hocko
2017-04-07 14:32 ` Jerome Glisse
2017-04-07 14:45 ` Michal Hocko
2017-04-07 14:57 ` Jerome Glisse
2017-04-07 15:11 ` Michal Hocko
2017-04-07 16:10 ` Jerome Glisse
2017-04-07 16:37 ` Michal Hocko
2017-04-07 17:10 ` Jerome Glisse
2017-04-07 17:59 ` Michal Hocko
2017-04-07 18:27 ` Jerome Glisse
2017-04-05 20:40 ` Jérôme Glisse [this message]
2017-04-05 20:40 ` [HMM 03/16] mm/unaddressable-memory: new type of ZONE_DEVICE for unaddressable memory Jérôme Glisse
2017-04-05 20:40 ` [HMM 04/16] mm/ZONE_DEVICE/x86: add support for un-addressable device memory Jérôme Glisse
2017-04-05 20:40 ` [HMM 05/16] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-04-05 20:40 ` [HMM 06/16] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-04-05 20:40 ` [HMM 07/16] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-04-05 20:40 ` [HMM 08/16] mm/hmm: heterogeneous memory management (HMM for short) Jérôme Glisse
2017-04-05 20:40 ` [HMM 09/16] mm/hmm/mirror: mirror process address space on device with HMM helpers Jérôme Glisse
2017-04-05 20:40 ` [HMM 10/16] mm/hmm/mirror: helper to snapshot CPU page table v2 Jérôme Glisse
2017-04-10 8:35 ` Michal Hocko
2017-04-10 8:43 ` Michal Hocko
2017-04-10 22:10 ` Andrew Morton
2017-04-11 1:33 ` Jerome Glisse
2017-04-11 20:33 ` Andrew Morton
2017-04-05 20:40 ` [HMM 11/16] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-04-05 20:40 ` [HMM 12/16] mm/migrate: support un-addressable ZONE_DEVICE page in migration Jérôme Glisse
2017-04-05 20:40 ` [HMM 13/16] mm/migrate: allow migrate_vma() to alloc new page on empty entry Jérôme Glisse
2017-04-05 20:40 ` [HMM 14/16] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE Jérôme Glisse
2017-04-06 21:22 ` Jerome Glisse
2017-04-07 1:37 ` Balbir Singh
2017-04-07 2:02 ` Jerome Glisse
2017-04-07 16:26 ` Jerome Glisse
2017-04-10 4:31 ` Balbir Singh
2017-04-05 20:40 ` [HMM 15/16] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v2 Jérôme Glisse
2017-04-05 20:40 ` [HMM 16/16] hmm: heterogeneous memory management documentation Jérôme Glisse
[not found] ` <CAF7GXvptCfV89rAi=j1cy1df12039GDpq_DHOyx+_xk0FjBDPg@mail.gmail.com>
2017-04-06 4:59 ` [HMM 00/16] HMM (Heterogeneous Memory Management) v19 Jerome Glisse
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