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authorToshi Kani <toshi.kani@hpe.com>2017-02-04 00:13:20 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-04 01:13:19 +0300
commitdeb88a2a19e85842d79ba96b05031739ec327ff4 (patch)
tree159f389128e80e284f151689651e78eefa747e41
parent35f860f9ba6aac56cc38e8b18916d833a83f1157 (diff)
downloadlinux-deb88a2a19e85842d79ba96b05031739ec327ff4.tar.xz
mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
Patch series "fix a kernel oops when reading sysfs valid_zones", v2. A sysfs memory file is created for each 2GiB memory block on x86-64 when the system has 64GiB or more memory. [1] When the start address of a memory block is not backed by struct page, i.e. a memory range is not aligned by 2GiB, reading its 'valid_zones' attribute file leads to a kernel oops. This issue was observed on multiple x86-64 systems with more than 64GiB of memory. This patch-set fixes this issue. Patch 1 first fixes an issue in test_pages_in_a_zone(), which does not test the start section. Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone() to return valid [start, end). Note for stable kernels: The memory block size change was made by commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems"), which was accepted to 3.9. However, this patch-set depends on (and fixes) the change to test_pages_in_a_zone() made by commit 5f0f2887f4de ("mm/memory_hotplug.c: check for missing sections in test_pages_in_a_zone()"), which was accepted to 4.4. So, I recommend that we backport it up to 4.4. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' This patch (of 2): test_pages_in_a_zone() does not check 'start_pfn' when it is aligned by section since 'sec_end_pfn' is set equal to 'pfn'. Since this function is called for testing the range of a sysfs memory file, 'start_pfn' is always aligned by section. Fix it by properly setting 'sec_end_pfn' to the next section pfn. Also make sure that this function returns 1 only when the range belongs to a zone. Link: http://lkml.kernel.org/r/20170127222149.30893-2-toshi.kani@hpe.com Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Andrew Banman <abanman@sgi.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: Greg KH <greg@kroah.com> Cc: <stable@vger.kernel.org> [4.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memory_hotplug.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index ca2723d47338..1218f73890b6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1483,7 +1483,7 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
}
/*
- * Confirm all pages in a range [start, end) is belongs to the same zone.
+ * Confirm all pages in a range [start, end) belong to the same zone.
*/
int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
{
@@ -1491,9 +1491,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
struct zone *zone = NULL;
struct page *page;
int i;
- for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
+ for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
pfn < end_pfn;
- pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
+ pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
/* Make sure the memory section is present first */
if (!present_section_nr(pfn_to_section_nr(pfn)))
continue;
@@ -1512,7 +1512,11 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
zone = page_zone(page);
}
}
- return 1;
+
+ if (zone)
+ return 1;
+ else
+ return 0;
}
/*