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Date: Mon, 10 Dec 2007 15:38:20 +0100 From: Christian Borntraeger <borntraeger@...ibm.com> To: Nick Piggin <npiggin@...e.de> Cc: Andrew Morton <akpm@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-fsdevel@...r.kernel.org, "Eric W. Biederman" <ebiederm@...ssion.com>, rob@...dley.net, Jens Axboe <axboe@...nel.dk>, cotte@...ibm.com Subject: Re: [patch] mm: fix XIP file writes Hi Nick, > Here we go. See, brd already found a bug ;) > Can you apply the ext2 XIP patch too? And I'll resend the brd XIP patch. [...] > Writing to XIP files at a non-page-aligned offset results in data corruption > because the writes were always sent to the start of the page. [...] > @@ -314,7 +314,7 @@ __xip_file_write(struct file *filp, cons > fault_in_pages_readable(buf, bytes); > kaddr = kmap_atomic(page, KM_USER0); > copied = bytes - > - __copy_from_user_inatomic_nocache(kaddr, buf, bytes); > + __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes); > kunmap_atomic(kaddr, KM_USER0); > flush_dcache_page(page); I asked myself why this problem never happened before. So I asked our testers to reproduce this problem on 2.6.23 and service levels. As the testcase did not trigger, I looked into the 2.6.23 code. This problem was introduced by commit 4a9e5ef1f4f15205e477817a5cefc34bd3f65f55 (mm: write iovec cleanup from Nick Piggin) during 2.6.24-rc: --------snip------- - copied = filemap_copy_from_user(page, offset, buf, bytes); [...] + copied = bytes - + __copy_from_user_inatomic_nocache(kaddr, buf, bytes); ------------------- So yes, its good to have xip on brd. It even tests your changes ;-) Good news is, that we dont need anything for stable. Christian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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