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authorTony Luck <tony.luck@intel.com>2017-08-16 10:18:03 -0700
committerIngo Molnar <mingo@kernel.org>2017-08-17 10:30:49 +0200
commitce0fa3e56ad20f04d8252353dcd24e924abdafca (patch)
treedee3cdb69e839f4eb1dc5690deb7e145202124c7 /mm/memory-failure.c
parentacpi, x86/mm: Remove encryption mask from ACPI page protection type (diff)
downloadlinux-dev-ce0fa3e56ad20f04d8252353dcd24e924abdafca.tar.xz
linux-dev-ce0fa3e56ad20f04d8252353dcd24e924abdafca.zip
x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages
Speculative processor accesses may reference any memory that has a valid page table entry. While a speculative access won't generate a machine check, it will log the error in a machine check bank. That could cause escalation of a subsequent error since the overflow bit will be then set in the machine check bank status register. Code has to be double-plus-tricky to avoid mentioning the 1:1 virtual address of the page we want to map out otherwise we may trigger the very problem we are trying to avoid. We use a non-canonical address that passes through the usual Linux table walking code to get to the same "pte". Thanks to Dave Hansen for reviewing several iterations of this. Also see: http://marc.info/?l=linux-mm&m=149860136413338&w=2 Signed-off-by: Tony Luck <tony.luck@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Elliott, Robert (Persistent Memory) <elliott@hpe.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20170816171803.28342-1-tony.luck@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to '')
-rw-r--r--mm/memory-failure.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1cd3b3569af8..88366626c0b7 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1146,6 +1146,8 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
return 0;
}
+ arch_unmap_kpfn(pfn);
+
orig_head = hpage = compound_head(p);
num_poisoned_pages_inc();