4.9-stable review patch. If anyone has any objections, please let me know.
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From: Vlastimil Babka vbabka@suse.cz
commit 9df9516940a61d29aedf4d91b483ca6597e7d480 upstream.
On 32bit PAE kernels on 64bit hardware with enough physical bits, l1tf_pfn_limit() will overflow unsigned long. This in turn affects max_swapfile_size() and can lead to swapon returning -EINVAL. This has been observed in a 32bit guest with 42 bits physical address size, where max_swapfile_size() overflows exactly to 1 << 32, thus zero, and produces the following warning to dmesg:
[ 6.396845] Truncating oversized swap area, only using 0k out of 2047996k
Fix this by using unsigned long long instead.
Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf") Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2") Reported-by: Dominique Leuenberger dimstar@suse.de Reported-by: Adrian Schroeter adrian@suse.de Signed-off-by: Vlastimil Babka vbabka@suse.cz Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Andi Kleen ak@linux.intel.com Acked-by: Michal Hocko mhocko@suse.com Cc: "H . Peter Anvin" hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Dave Hansen dave.hansen@intel.com Cc: Michal Hocko mhocko@kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180820095835.5298-1-vbabka@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/processor.h | 4 ++-- arch/x86/mm/init.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)
--- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -173,9 +173,9 @@ extern const struct seq_operations cpuin
extern void cpu_detect(struct cpuinfo_x86 *c);
-static inline unsigned long l1tf_pfn_limit(void) +static inline unsigned long long l1tf_pfn_limit(void) { - return BIT(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; + return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1; }
extern void early_cpu_init(void); --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -792,7 +792,7 @@ unsigned long max_swapfile_size(void)
if (boot_cpu_has_bug(X86_BUG_L1TF)) { /* Limit the swap file size to MAX_PA/2 for L1TF workaround */ - unsigned long l1tf_limit = l1tf_pfn_limit() + 1; + unsigned long long l1tf_limit = l1tf_pfn_limit() + 1; /* * We encode swap offsets also with 3 bits below those for pfn * which makes the usable limit higher. @@ -800,7 +800,7 @@ unsigned long max_swapfile_size(void) #if CONFIG_PGTABLE_LEVELS > 2 l1tf_limit <<= PAGE_SHIFT - SWP_OFFSET_FIRST_BIT; #endif - pages = min_t(unsigned long, l1tf_limit, pages); + pages = min_t(unsigned long long, l1tf_limit, pages); } return pages; }