From: Dexuan Cui <decui@xxxxxxxxxxxxx> commit d1cd1210834649ce1ca6bafe5ac25d2f40331343 upstream. pte_pfn() returns a PFN of long (32 bits in 32-PAE), so "long << PAGE_SHIFT" will overflow for PFNs above 4GB. Due to this issue, some Linux 32-PAE distros, running as guests on Hyper-V, with 5GB memory assigned, can't load the netvsc driver successfully and hence the synthetic network device can't work (we can use the kernel parameter mem=3000M to work around the issue). Cast pte_pfn() to phys_addr_t before shifting. Fixes: "commit d76565344512: x86, mm: Create slow_virt_to_phys()" Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> Cc: gregkh@xxxxxxxxxxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: olaf@xxxxxxxxx Cc: apw@xxxxxxxxxxxxx Cc: jasowang@xxxxxxxxxx Cc: dave.hansen@xxxxxxxxx Cc: riel@xxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1414580017-27444-1-git-send-email-decui@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> --- 7u/arch/x86/mm/pageattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/7u/arch/x86/mm/pageattr.c b/7u/arch/x86/mm/pageattr.c index 4ed2b2d..81b82f4 100644 --- a/7u/arch/x86/mm/pageattr.c +++ b/7u/arch/x86/mm/pageattr.c @@ -405,7 +405,7 @@ phys_addr_t slow_virt_to_phys(void *__virt_addr) psize = page_level_size(level); pmask = page_level_mask(level); offset = virt_addr & ~pmask; - phys_addr = pte_pfn(*pte) << PAGE_SHIFT; + phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT; return (phys_addr | offset); } EXPORT_SYMBOL_GPL(slow_virt_to_phys); -- 1.8.3.1
