From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch 1/6] md: remove dependency on __GFP_NOFAIL Date: Mon, 23 Aug 2010 12:26:06 -0700 Message-ID: <20100823122606.47524cef.akpm@linux-foundation.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: David Rientjes Cc: Neil Brown , Alasdair G Kergon , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids On Mon, 16 Aug 2010 19:57:51 -0700 (PDT) David Rientjes wrote: > Removes the dependency on __GFP_NOFAIL by looping indefinitely in the > caller. > > Signed-off-by: David Rientjes > --- > drivers/md/dm-region-hash.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c > --- a/drivers/md/dm-region-hash.c > +++ b/drivers/md/dm-region-hash.c > @@ -289,8 +289,12 @@ static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region) > struct dm_region *reg, *nreg; > > nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC); > - if (unlikely(!nreg)) > - nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL); > + if (unlikely(!nreg)) { > + /* FIXME: this may potentially loop forever */ > + do { > + nreg = kmalloc(sizeof(*nreg), GFP_NOIO); > + } while (!nreg); > + } > > nreg->state = rh->log->type->in_sync(rh->log, region, 1) ? > DM_RH_CLEAN : DM_RH_NOSYNC; erm. The reason for adding GFP_NOFAIL in the first place was my observation that the kernel contained lots of open-coded retry-for-ever loops. All of these are wrong, bad, buggy and mustfix. So we consolidated the wrongbadbuggymustfix concept into the core MM so that miscreants could be easily identified and hopefully fixed. I think that simply undoing that change is a bad idea - it allows the wrongbadbuggymustfix code to hide from view. The correct way to remove __GFP_NOFAIL is to fix the wrongbadbuggymustfix code properly.