From: Andrea Arcangeli <andrea@suse.de>
To: Jens Axboe <axboe@suse.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org,
"ZINKEVICIUS,MATT (HP-Loveland,ex1)" <matt_zinkevicius@hp.com>
Subject: Re: patch: highmem zero-bounce
Date: Wed, 27 Jun 2001 11:41:55 +0200 [thread overview]
Message-ID: <20010627114155.A31910@athlon.random> (raw)
In-Reply-To: <20010626182215.C14460@suse.de>
In-Reply-To: <20010626182215.C14460@suse.de>; from axboe@suse.de on Tue, Jun 26, 2001 at 06:22:15PM +0200
On Tue, Jun 26, 2001 at 06:22:15PM +0200, Jens Axboe wrote:
> Hi,
>
> I updated the patches to 2.4.6-pre5, and removed the zone-dma32
> addition. This means that machines with > 4GB of RAM will need to go all
good, we can relax the ZONE_NORMAL later, that's a separate problem with
skipping the bounces.
I can see one mm corruption race condition in the patch, you missed
nested irq in the for kmap_irq_bh (PIO). You must _always_
__cli/__save_flags before accessing the KMAP_IRQ_BH slot, in case the
remapping is required (so _only_ when the page is in the highmem zone).
Otherwise memory corruption will happen when the race triggers (for
example two ide disks in PIO mode doing I/O at the same time connected
to different irq sources).
Andrea
WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <andrea@suse.de>
To: Jens Axboe <axboe@suse.de>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org,
"ZINKEVICIUS,MATT (HP-Loveland,ex1)" <matt_zinkevicius@hp.com>
Subject: Re: patch: highmem zero-bounce
Date: Wed, 27 Jun 2001 11:41:55 +0200 [thread overview]
Message-ID: <20010627114155.A31910@athlon.random> (raw)
In-Reply-To: <20010626182215.C14460@suse.de>; from axboe@suse.de on Tue, Jun 26, 2001 at 06:22:15PM +0200
On Tue, Jun 26, 2001 at 06:22:15PM +0200, Jens Axboe wrote:
> Hi,
>
> I updated the patches to 2.4.6-pre5, and removed the zone-dma32
> addition. This means that machines with > 4GB of RAM will need to go all
good, we can relax the ZONE_NORMAL later, that's a separate problem with
skipping the bounces.
I can see one mm corruption race condition in the patch, you missed
nested irq in the for kmap_irq_bh (PIO). You must _always_
__cli/__save_flags before accessing the KMAP_IRQ_BH slot, in case the
remapping is required (so _only_ when the page is in the highmem zone).
Otherwise memory corruption will happen when the race triggers (for
example two ide disks in PIO mode doing I/O at the same time connected
to different irq sources).
Andrea
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next prev parent reply other threads:[~2001-06-27 9:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-26 16:22 patch: highmem zero-bounce Jens Axboe
2001-06-27 9:41 ` Andrea Arcangeli [this message]
2001-06-27 9:41 ` Andrea Arcangeli
2001-06-27 16:27 ` Jens Axboe
2001-06-27 16:27 ` Jens Axboe
2001-06-27 16:49 ` Jens Axboe
2001-06-27 17:06 ` Andrea Arcangeli
2001-06-27 17:06 ` Andrea Arcangeli
2001-06-27 17:12 ` Jens Axboe
2001-06-27 17:12 ` Jens Axboe
2001-07-06 13:41 ` Andrea Arcangeli
2001-07-06 13:41 ` Andrea Arcangeli
2001-07-06 13:45 ` Jens Axboe
2001-07-06 13:45 ` Jens Axboe
2001-07-06 13:58 ` Andrea Arcangeli
2001-07-06 13:58 ` Andrea Arcangeli
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