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284ce4011b
Currently memory_failure() returns zero if the error was handled. On that result mce_unmap_kpfn() is called to zap the page out of the kernel linear mapping to prevent speculative fetches of potentially poisoned memory. However, in the case of dax mapped devmap pages the page may be in active permanent use by the device driver, so it cannot be unmapped from the kernel. Instead of marking the page not present, marking the page UC should be sufficient for preventing poison from being pre-fetched into the cache. Convert mce_unmap_pfn() to set_mce_nospec() remapping the page as UC, to hide it from speculative accesses. Given that that persistent memory errors can be cleared by the driver, include a facility to restore the page to cacheable operation, clear_mce_nospec(). Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: <linux-edac@vger.kernel.org> Cc: <x86@kernel.org> Acked-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Ingo Molnar <mingo@redhat.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> |
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