linux-kernel - Re: [PATCH 2/4] mm/vmalloc: add support for __GFP

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Date:   Tue, 26 Oct 2021 21:30:52 +1100
From:   "NeilBrown" <neilb@...e.de>
To:     "Michal Hocko" <mhocko@...e.com>
Cc:     linux-mm@...ck.org, "Dave Chinner" <david@...morbit.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        "Christoph Hellwig" <hch@...radead.org>,
        "Uladzislau Rezki" <urezki@...il.com>,
        linux-fsdevel@...r.kernel.org,
        "LKML" <linux-kernel@...r.kernel.org>,
        "Ilya Dryomov" <idryomov@...il.com>,
        "Jeff Layton" <jlayton@...nel.org>
Subject: Re: [PATCH 2/4] mm/vmalloc: add support for __GFP_NOFAIL

On Tue, 26 Oct 2021, Michal Hocko wrote:
> On Tue 26-10-21 09:59:36, Neil Brown wrote:
> > On Tue, 26 Oct 2021, Michal Hocko wrote:
> [...]
> > > @@ -3032,6 +3036,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
> > >  		warn_alloc(gfp_mask, NULL,
> > >  			"vmalloc error: size %lu, vm_struct allocation failed",
> > >  			real_size);
> > > +		if (gfp_mask & __GFP_NOFAIL) {
> > > +			schedule_timeout_uninterruptible(1);
> > > +			goto again;
> > > +		}
> > 
> > Shouldn't the retry happen *before* the warning?
> 
> I've done it after to catch the "depleted or fragmented" vmalloc space.
> This is not related to the memory available and therefore it won't be
> handled by the oom killer. The error message shouldn't imply the vmalloc
> allocation failure IMHO but I am open to suggestions.

The word "failed" does seem to imply what you don't want it to imply...

I guess it is reasonable to have this warning, but maybe add " -- retrying"
if __GFP_NOFAIL.

Thanks,
NeilBrown