Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755587AbaGaHCm (ORCPT ); Thu, 31 Jul 2014 03:02:42 -0400 Received: from mail-ig0-f179.google.com ([209.85.213.179]:34112 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbaGaHCk (ORCPT ); Thu, 31 Jul 2014 03:02:40 -0400 Date: Thu, 31 Jul 2014 00:02:38 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Chintan Pandya cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2] mm: BUG when __kmap_atomic_idx equals KM_TYPE_NR In-Reply-To: <1406787871-2951-1-git-send-email-cpandya@codeaurora.org> Message-ID: References: <1406787871-2951-1-git-send-email-cpandya@codeaurora.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Jul 2014, Chintan Pandya wrote: > __kmap_atomic_idx is per_cpu variable. Each CPU can > use KM_TYPE_NR entries from FIXMAP i.e. from 0 to > KM_TYPE_NR - 1. Allowing __kmap_atomic_idx to over- > shoot to KM_TYPE_NR can mess up with next CPU's 0th > entry which is a bug. Hence BUG_ON if > __kmap_atomic_idx >= KM_TYPE_NR. > This appears to be a completely different patch, not a v2. Why is this check only done for CONFIG_DEBUG_HIGHMEM? I think Andrew's comment earlier was referring to the changelog only and not the patch, which looked correct. > Signed-off-by: Chintan Pandya > --- > Changes: > > V1 --> V2 > > Not touching CONFIG_DEBUG_HIGHMEM. > > include/linux/highmem.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 7fb31da..9286a46 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -93,7 +93,7 @@ static inline int kmap_atomic_idx_push(void) > > #ifdef CONFIG_DEBUG_HIGHMEM > WARN_ON_ONCE(in_irq() && !irqs_disabled()); > - BUG_ON(idx > KM_TYPE_NR); > + BUG_ON(idx >= KM_TYPE_NR); > #endif > return idx; > } -- 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/