From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [patch] x86/efi: use GFP_ATOMIC under spin_lock Date: Fri, 7 Mar 2014 13:10:22 +0100 Message-ID: <20140307121022.GA32575@gmail.com> References: <20140307112055.GE2351@elgon.mountain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20140307112055.GE2351-mgFCXtclrQlZLf2FXnZxJA@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dan Carpenter Cc: Matt Fleming , Nathan Zimmer , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-janitors-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-efi@vger.kernel.org * Dan Carpenter wrote: > In phys_efi_get_time() we call efi_call_phys_prelog() with a spin_lock > so this allocation should be atomic. > > Fixes: b8f2c21db390 ('efi, x86: Pass a proper identity mapping in efi_call_phys_prelog') > Signed-off-by: Dan Carpenter > > diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c > index 0c2a234fef1e..f5adcadb381b 100644 > --- a/arch/x86/platform/efi/efi_64.c > +++ b/arch/x86/platform/efi/efi_64.c > @@ -90,7 +90,7 @@ void __init efi_call_phys_prelog(void) > local_irq_save(efi_flags); > > n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE); > - save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_KERNEL); > + save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_ATOMIC); > > for (pgd = 0; pgd < n_pgds; pgd++) { > save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE); The allocation there, if it happens within a spinlocked path, is probably a layering violation - and GFP_ATOMIC is at best a workaround. Thanks, Ingo