Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758936Ab3GZNHh (ORCPT ); Fri, 26 Jul 2013 09:07:37 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57237 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758914Ab3GZNHX (ORCPT ); Fri, 26 Jul 2013 09:07:23 -0400 Date: Fri, 26 Jul 2013 15:07:21 +0200 From: Michal Hocko To: Johannes Weiner Cc: Andrew Morton , David Rientjes , KAMEZAWA Hiroyuki , azurIt , linux-mm@kvack.org, cgroups@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 2/6] arch: mm: do not invoke OOM killer on kernel fault OOM Message-ID: <20130726130721.GD17761@dhcp22.suse.cz> References: <1374791138-15665-1-git-send-email-hannes@cmpxchg.org> <1374791138-15665-3-git-send-email-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1374791138-15665-3-git-send-email-hannes@cmpxchg.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4895 Lines: 172 On Thu 25-07-13 18:25:34, Johannes Weiner wrote: > Kernel faults are expected to handle OOM conditions gracefully (gup, > uaccess etc.), so they should never invoke the OOM killer. Reserve > this for faults triggered in user context when it is the only option. > > Most architectures already do this, fix up the remaining few. > > Signed-off-by: Johannes Weiner I didn't go over all architectures to check whether something slipped through but the converted ones look OK to me. Reviewed-by: Michal Hocko > --- > arch/arm/mm/fault.c | 14 +++++++------- > arch/arm64/mm/fault.c | 14 +++++++------- > arch/avr32/mm/fault.c | 2 +- > arch/mips/mm/fault.c | 2 ++ > arch/um/kernel/trap.c | 2 ++ > arch/unicore32/mm/fault.c | 14 +++++++------- > 6 files changed, 26 insertions(+), 22 deletions(-) > > diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c > index c97f794..217bcbf 100644 > --- a/arch/arm/mm/fault.c > +++ b/arch/arm/mm/fault.c > @@ -349,6 +349,13 @@ retry: > if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) > return 0; > > + /* > + * If we are in kernel mode at this point, we > + * have no context to handle this fault with. > + */ > + if (!user_mode(regs)) > + goto no_context; > + > if (fault & VM_FAULT_OOM) { > /* > * We ran out of memory, call the OOM killer, and return to > @@ -359,13 +366,6 @@ retry: > return 0; > } > > - /* > - * If we are in kernel mode at this point, we > - * have no context to handle this fault with. > - */ > - if (!user_mode(regs)) > - goto no_context; > - > if (fault & VM_FAULT_SIGBUS) { > /* > * We had some memory, but were unable to > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index 0ecac89..dab1cfd 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -294,6 +294,13 @@ retry: > VM_FAULT_BADACCESS)))) > return 0; > > + /* > + * If we are in kernel mode at this point, we have no context to > + * handle this fault with. > + */ > + if (!user_mode(regs)) > + goto no_context; > + > if (fault & VM_FAULT_OOM) { > /* > * We ran out of memory, call the OOM killer, and return to > @@ -304,13 +311,6 @@ retry: > return 0; > } > > - /* > - * If we are in kernel mode at this point, we have no context to > - * handle this fault with. > - */ > - if (!user_mode(regs)) > - goto no_context; > - > if (fault & VM_FAULT_SIGBUS) { > /* > * We had some memory, but were unable to successfully fix up > diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c > index b2f2d2d..2ca27b0 100644 > --- a/arch/avr32/mm/fault.c > +++ b/arch/avr32/mm/fault.c > @@ -228,9 +228,9 @@ no_context: > */ > out_of_memory: > up_read(&mm->mmap_sem); > - pagefault_out_of_memory(); > if (!user_mode(regs)) > goto no_context; > + pagefault_out_of_memory(); > return; > > do_sigbus: > diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c > index 85df1cd..94d3a31 100644 > --- a/arch/mips/mm/fault.c > +++ b/arch/mips/mm/fault.c > @@ -241,6 +241,8 @@ out_of_memory: > * (which will retry the fault, or kill us if we got oom-killed). > */ > up_read(&mm->mmap_sem); > + if (!user_mode(regs)) > + goto no_context; > pagefault_out_of_memory(); > return; > > diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c > index 089f398..b2f5adf 100644 > --- a/arch/um/kernel/trap.c > +++ b/arch/um/kernel/trap.c > @@ -124,6 +124,8 @@ out_of_memory: > * (which will retry the fault, or kill us if we got oom-killed). > */ > up_read(&mm->mmap_sem); > + if (!is_user) > + goto out_nosemaphore; > pagefault_out_of_memory(); > return 0; > } > diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c > index f9b5c10..8ed3c45 100644 > --- a/arch/unicore32/mm/fault.c > +++ b/arch/unicore32/mm/fault.c > @@ -278,6 +278,13 @@ retry: > (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) > return 0; > > + /* > + * If we are in kernel mode at this point, we > + * have no context to handle this fault with. > + */ > + if (!user_mode(regs)) > + goto no_context; > + > if (fault & VM_FAULT_OOM) { > /* > * We ran out of memory, call the OOM killer, and return to > @@ -288,13 +295,6 @@ retry: > return 0; > } > > - /* > - * If we are in kernel mode at this point, we > - * have no context to handle this fault with. > - */ > - if (!user_mode(regs)) > - goto no_context; > - > if (fault & VM_FAULT_SIGBUS) { > /* > * We had some memory, but were unable to > -- > 1.8.3.2 > -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/