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Date: Wed, 02 Sep 2015 00:51:10 -0600 From: "Jan Beulich" <JBeulich@...e.com> To: "Andy Lutomirski" <luto@...capital.net> Cc: "David Vrabel" <david.vrabel@...rix.com>, "Ingo Molnar" <mingo@...e.hu>, "Andrew Lutomirski" <luto@...nel.org>, "Thomas Gleixner" <tglx@...utronix.de>, "Boris Ostrovsky" <boris.ostrovsky@...cle.com>, "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "H. Peter Anvin" <hpa@...or.com> Subject: Re: [PATCH] x86: fix small LDT allocation for Xen >>> On 01.09.15 at 21:37, <luto@...capital.net> wrote: > On Tue, Sep 1, 2015 at 3:48 AM, Jan Beulich <JBeulich@...e.com> wrote: >> While 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(). >> >> Signed-off-by: Jan Beulich <jbeulich@...e.com> >> Cc: Andy Lutomirski <luto@...nel.org> >> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com> >> Cc: David Vrabel <david.vrabel@...rix.com> >> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> >> --- >> arch/x86/kernel/ldt.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> --- 4.2/arch/x86/kernel/ldt.c >> +++ 4.2-x86-LDT-alloc/arch/x86/kernel/ldt.c >> @@ -58,7 +58,7 @@ static struct ldt_struct *alloc_ldt_stru >> 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_free_page(GFP_KERNEL|__GFP_ZERO); > > This would need a corresponding change to the kfree path, right? Oops - yes of course. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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