From: Dexuan Cui <decui@microsoft.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, x86@kernel.org, olaf@aepfle.de,
apw@canonical.com, jasowang@redhat.com, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com, dave.hansen@intel.com,
riel@redhat.com
Cc: kys@microsoft.com, haiyangz@microsoft.com
Subject: [PATCH] x86, pageattr: fix slow_virt_to_phys() for X86_PAE
Date: Wed, 29 Oct 2014 03:53:37 -0700 [thread overview]
Message-ID: <1414580017-27444-1-git-send-email-decui@microsoft.com> (raw)
pte_pfn() returns a PFN of long (32 bits in 32-PAE), then
"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).
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
arch/x86/mm/pageattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index ae242a7..36de293 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -409,7 +409,7 @@ 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);
--
1.9.1
next reply other threads:[~2014-10-29 9:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-29 10:53 Dexuan Cui [this message]
2014-10-29 10:00 ` [tip:x86/urgent] x86, pageattr: Prevent overflow in slow_virt_to_phys() for X86_PAE tip-bot for Dexuan Cui
2014-10-29 10:53 [PATCH] x86, pageattr: fix " Dexuan Cui
2014-10-29 9:50 ` Dexuan Cui
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