From: Jens Axboe <axboe@kernel.dk>
To: Hugh Dickins <hughd@google.com>
Cc: Kent Overstreet <kmo@daterainc.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Shaohua Li <shli@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: next bio iters break discard?
Date: Fri, 31 Jan 2014 14:58:30 -0700 [thread overview]
Message-ID: <20140131215830.GB24191@kernel.dk> (raw)
In-Reply-To: <alpine.LSU.2.11.1401310852000.987@eggly.anvils>
On Fri, Jan 31 2014, Hugh Dickins wrote:
> On Thu, 16 Jan 2014, Kent Overstreet wrote:
> >
> > Ok, I reread the code and figured it out - the analagous change also has to be
> > made in __blk_segment_map_sg(). I'll mail out a patch for this tomorrow after
> > I've stared at the code more and had less beer.
>
> I'd been hoping for a patch to try, but now your changes have hit Linus's
> tree: so today we have discard broken there too, crashing as originally
> reported on the NULL struct page pointer in __blk_recalc_rq_segments()'s
> page_to_pfn(bv.bv_page).
>
> How to reproduce it? I hope you'll find easier ways, but I get it with
> swapping to SSD (remember "swapon -d" to enable discard). I'm just doing
> what I've done for years, running a pair of make -j20 kbuilds to tmpfs in
> limited RAM (I use mem=700M with 1.5G of swap: but that would be far too
> little RAM for a general config of current tree), to get plenty of fairly
> chaotic swapping but good forward progress nonetheless (if the sizes are
> too small, then it'll just thrash abysmally or be OOM-killed).
>
> But please do send me a patch and I'll give it a try - thanks.
Hugh, sorry about that, this particular issue slipped my mind. Will get
this fixed up as soon as possible, hopefully before -rc1...
--
Jens Axboe
next prev parent reply other threads:[~2014-01-31 21:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-13 3:52 Hugh Dickins
2014-01-14 2:33 ` Kent Overstreet
2014-01-14 4:06 ` Martin K. Petersen
2014-01-14 4:48 ` Kent Overstreet
2014-01-14 20:17 ` Martin K. Petersen
2014-01-14 22:24 ` Kent Overstreet
2014-01-16 1:39 ` Martin K. Petersen
2014-01-16 20:21 ` Hugh Dickins
2014-01-17 1:06 ` Kent Overstreet
2014-01-17 1:21 ` Kent Overstreet
2014-01-31 17:17 ` Hugh Dickins
2014-01-31 21:58 ` Jens Axboe [this message]
2014-02-04 10:17 ` [PATCH] block: Explicitly handle discard/write same segments Kent Overstreet
2014-02-04 12:25 ` Hugh Dickins
2014-02-04 12:35 ` Kent Overstreet
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