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From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@lists.01.org
Cc: Michal Hocko <mhocko@suse.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	hch@lst.de, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	jack@suse.cz
Subject: [PATCH v3 06/12] mm, madvise_inject_error: Let memory_failure() optionally take a page reference
Date: Mon, 04 Jun 2018 16:12:12 -0700	[thread overview]
Message-ID: <152815393199.39010.5209788235715575901.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <152815389835.39010.13253559944508110923.stgit@dwillia2-desk3.amr.corp.intel.com>

The madvise_inject_error() routine uses get_user_pages() to lookup the
pfn and other information for injected error, but it does not release
that pin. The assumption is that failed pages should be taken out of
circulation.

However, for dax mappings it is not possible to take pages out of
circulation since they are 1:1 physically mapped as filesystem blocks,
or device-dax capacity. They also typically represent persistent memory
which has an error clearing capability.

In preparation for adding a special handler for dax mappings, shift the
responsibility of taking the page reference to memory_failure(). I.e.
drop the page reference and do not specify MF_COUNT_INCREASED to
memory_failure().

Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 mm/madvise.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 4d3c922ea1a1..b731933dddae 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -631,11 +631,13 @@ static int madvise_inject_error(int behavior,
 
 
 	for (; start < end; start += PAGE_SIZE << order) {
+		unsigned long pfn;
 		int ret;
 
 		ret = get_user_pages_fast(start, 1, 0, &page);
 		if (ret != 1)
 			return ret;
+		pfn = page_to_pfn(page);
 
 		/*
 		 * When soft offlining hugepages, after migrating the page
@@ -651,17 +653,27 @@ static int madvise_inject_error(int behavior,
 
 		if (behavior == MADV_SOFT_OFFLINE) {
 			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
-						page_to_pfn(page), start);
+					pfn, start);
 
 			ret = soft_offline_page(page, MF_COUNT_INCREASED);
 			if (ret)
 				return ret;
 			continue;
 		}
+
 		pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
-						page_to_pfn(page), start);
+				pfn, start);
+
+		ret = memory_failure(pfn, 0);
+
+		/*
+		 * Drop the page reference taken by get_user_pages_fast(). In
+		 * the absence of MF_COUNT_INCREASED the memory_failure()
+		 * routine is responsible for pinning the page to prevent it
+		 * from being released back to the page allocator.
+		 */
+		put_page(page);
 
-		ret = memory_failure(page_to_pfn(page), MF_COUNT_INCREASED);
 		if (ret)
 			return ret;
 	}

  parent reply	other threads:[~2018-06-04 23:12 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-04 23:11 [PATCH v3 00/12] mm: Teach memory_failure() about ZONE_DEVICE pages Dan Williams
2018-06-04 23:11 ` [PATCH v3 01/12] device-dax: Convert to vmf_insert_mixed and vm_fault_t Dan Williams
2018-06-04 23:11 ` [PATCH v3 02/12] device-dax: Cleanup vm_fault de-reference chains Dan Williams
2018-06-04 23:11 ` [PATCH v3 03/12] device-dax: Enable page_mapping() Dan Williams
2018-06-07 15:39   ` Jan Kara
2018-06-04 23:12 ` [PATCH v3 04/12] device-dax: Set page->index Dan Williams
2018-06-07 15:50   ` Jan Kara
2018-06-04 23:12 ` [PATCH v3 05/12] filesystem-dax: " Dan Williams
2018-06-07 16:02   ` Jan Kara
2018-06-04 23:12 ` Dan Williams [this message]
2018-06-04 23:12 ` [PATCH v3 07/12] x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses Dan Williams
2018-06-04 23:12 ` [PATCH v3 08/12] x86/memory_failure: Introduce {set, clear}_mce_nospec() Dan Williams
2018-06-07  4:42   ` Dan Williams
2018-06-07 17:02     ` Luck, Tony
2018-06-04 23:12 ` [PATCH v3 09/12] mm, memory_failure: Pass page size to kill_proc() Dan Williams
2018-06-04 23:12 ` [PATCH v3 10/12] mm, memory_failure: Fix page->mapping assumptions relative to the page lock Dan Williams
2018-06-04 23:12 ` [PATCH v3 11/12] mm, memory_failure: Teach memory_failure() about dev_pagemap pages Dan Williams
2018-06-07  4:22   ` Dan Williams
2018-06-07 16:30   ` Jan Kara
2018-06-07 16:45     ` Dan Williams
2018-06-04 23:12 ` [PATCH v3 12/12] libnvdimm, pmem: Restore page attributes when clearing errors Dan Williams

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