linux-kernel - Re: [PATCH 2/2] hugetlb reservations: fix hugetlb MAP

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20080623080048.GJ21597@csn.ul.ie>
Date:	Mon, 23 Jun 2008 09:00:48 +0100
From:	Mel Gorman <mel@....ul.ie>
To:	Andy Whitcroft <apw@...dowen.org>
Cc:	Jon Tollefson <kniht@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>,
	Nishanth Aravamudan <nacc@...ibm.com>,
	Adam Litke <agl@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, kernel-testers@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 2/2] hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits

Typical. I spotted this after I pushed send.....

> <SNIP>

> @@ -266,14 +326,19 @@ static void decrement_hugepage_resv_vma(struct hstate *h,
>  		 * private mappings.
>  		 */
>  		if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
> -			unsigned long flags, reserve;
> +			unsigned long idx = vma_pagecache_offset(h,
> +							vma, address);
> +			struct resv_map *reservations = vma_resv_map(vma);
> +
>  			h->resv_huge_pages--;
> -			flags = (unsigned long)vma->vm_private_data &
> -							HPAGE_RESV_MASK;
> -			reserve = (unsigned long)vma->vm_private_data - 1;
> -			vma->vm_private_data = (void *)(reserve | flags);
> +
> +			/* Mark this page used in the map. */
> +			if (region_chg(&reservations->regions, idx, idx + 1) < 0)
> +				return -1;
> +			region_add(&reservations->regions, idx, idx + 1);
>  		}

decrement_hugepage_resv_vma() is called with hugetlb_lock held and region_chg
calls kmalloc(GFP_KERNEL).  Hence it's possible we would sleep with that
spinlock held which is a bit uncool. The allocation needs to happen outside
the lock. Right?

> <SNIP>

-- 
Mel Gorman
--
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/