From: Jan Beulich JBeulich@suse.com
[ Upstream commit f454b478861325f067fd58ba7ee9f1b5c4a9d6a0 ]
While the following commit:
37868fe113 ("x86/ldt: Make modify_ldt synchronous")
added a nice comment explaining that Xen needs page-aligned whole page chunks for guest descriptor tables, it then nevertheless used kzalloc() on the small size path.
As I'm unaware of guarantees for kmalloc(PAGE_SIZE, ) to return page-aligned memory blocks, I believe this needs to be switched back to __get_free_page() (or better get_zeroed_page()).
Signed-off-by: Jan Beulich jbeulich@suse.com Cc: Andy Lutomirski luto@amacapital.net Cc: Andy Lutomirski luto@kernel.org Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: David Vrabel david.vrabel@citrix.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/55E735D6020000780009F1E6@prv-mh.provo.novell.com Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/ldt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index 2bcc0525f1c1..6acc9dd91f36 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -58,7 +58,7 @@ static struct ldt_struct *alloc_ldt_struct(int size) if (alloc_size > PAGE_SIZE) new_ldt->entries = vzalloc(alloc_size); else - new_ldt->entries = kzalloc(PAGE_SIZE, GFP_KERNEL); + new_ldt->entries = (void *)get_zeroed_page(GFP_KERNEL);
if (!new_ldt->entries) { kfree(new_ldt); @@ -95,7 +95,7 @@ static void free_ldt_struct(struct ldt_struct *ldt) if (ldt->size * LDT_ENTRY_SIZE > PAGE_SIZE) vfree(ldt->entries); else - kfree(ldt->entries); + free_page((unsigned long)ldt->entries); kfree(ldt); }