From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikulas Patocka Subject: Re: [PATCH] block: fix q->max_segment_size checking in blk_recalc_rq_segments about VMERGE Date: Tue, 15 Jul 2008 11:46:46 -0400 (EDT) Message-ID: References: <20080715231956A.fujita.tomonori@lab.ntt.co.jp> <20080716003047P.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <20080716003047P.fujita.tomonori@lab.ntt.co.jp> Sender: linux-parisc-owner@vger.kernel.org To: FUJITA Tomonori Cc: jens.axboe@oracle.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, davem@davemloft.net, linux-parisc@vger.kernel.org List-Id: linux-scsi@vger.kernel.org >> Even if we fix it now, the question is: how long it will stay fixed? Until >> someone makes another change to struct device that restricts boundaries on >> some wacky hardware. > > I'm not sure how the boundary restriction of a device can break > the VMERGE accounting. Because block layer code doesn't know anything about the device, pci access restrictions and so on. Someone already broken DaveM's Sparc64 merging by adding boundaries (it was broken even before, but these boundary checks made it worse). Mikulas