lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 17 Aug 2012 18:33:46 +0200 From: Andrea Arcangeli <aarcange@...hat.com> To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, Andi Kleen <ak@...ux.intel.com>, "H. Peter Anvin" <hpa@...ux.intel.com>, linux-kernel@...r.kernel.org, "Kirill A. Shutemov" <kirill@...temov.name> Subject: Re: [PATCH, RFC 7/9] thp: implement splitting pmd for huge zero page On Fri, Aug 17, 2012 at 11:12:33AM +0300, Kirill A. Shutemov wrote: > I've used do_huge_pmd_wp_page_fallback() as template for my code. > What's difference between these two code paths? > Why is do_huge_pmd_wp_page_fallback() safe? Good point. do_huge_pmd_wp_page_fallback works only on the current "mm" so it doesn't need the splitting transition, but thinking twice the split_huge_zero_page_pmd also works only on the local "mm" because you're not really splitting the zero page there (you're not affecting other mm). As long as you keep holding the page_table_lock of the "mm" that you're altering your current version is safe. I got mistaken because I'm very used to think at split huge page as something that cannot relay on the page_table_lock, but this is a simpler case that isn't splitting the "page" but only the "pmd" of a single "mm", so you can safely relay on the mm->page_table_lock :). > Looks resonable. I'll update it in next revision. Thanks. Of course the function parameter comments to avoid unnecessary calls of find_vma, weren't related to the above locking issues. -- 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/
Powered by blists - more mailing lists