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Message-ID: <6101e8c40802291404u49037ad9u4347f552ce72bf28@mail.gmail.com>
Date: Fri, 29 Feb 2008 23:04:58 +0100
From: "Oliver Pinter" <oliver.pntr@gmail.com>
To: "Ingo Molnar" <mingo@elte.hu>
Subject: Re: x86: potential ioremap() issues
Cc: "Jan Beulich" <jbeulich@novell.com>, linux-kernel@vger.kernel.org,
       "Thomas Gleixner" <tglx@linutronix.de>,
       "H. Peter Anvin" <hpa@zytor.com>,
       "Arjan van de Ven" <arjan@infradead.org>
In-Reply-To: <20080228132404.GB18551@elte.hu>
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References: <47C6BE37.76E4.0078.0@novell.com> <20080228132404.GB18551@elte.hu>
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Hi Ingo!
this patch is needed for 2.6.22 kernel? I see, this code inarch/x86_64/mm/ioremap.c
/* a k?rd?s az, hogy ezt a patchet backportoljam 2.6.22 al? vagy ne?x86_64 alatt megtal?ltam a cser?lend? k?dr?szt... * k?sz?n?m a v?laszt */On 2/28/08, Ingo Molnar <mingo@elte.hu> wrote:>> * Jan Beulich <jbeulich@novell.com> wrote:>> > Ingo,> >> > with the new ioremap() implementation I see a couple of (potential)> > issues:> > - When ioremap_page_range() fails, remove_vm_area() is used rather> > than vunmap() - I think this will cause a 'struct vm_struct' leak.>> indeed, good catch - could you check whether the patch below fixes this?> I also pushed this out into x86.git#testing, which you can pick up via:>> http://people.redhat.com/mingo/x86.git/README>> > - While ioremap() continues to happily map RAM pages (with a bogus> > [see below] WARN_ON_ONCE()), cacheability of the memory is not> > being restored in iounmap().>> correct - these are never supposed to be 'true', generally allocated RAM> pages - or like we do with AGP where the pages are exclusively owned we> restore their cacheability explicitly.>> > - The check for RAM pages (except for the WARN_ON_ONCE())> > continues to be applied only to lowmem pages.>> yes, the biggest constraint from ioremap comes when it applies to pages> that are mapped by the kernel. But i guess we could extend this to all> things RAM ... the second patch below does this. What do you think? I've> queued this up in x86.git#testing as well.>> > - The WARN_ON_ONCE() itself is applied to the pfn after the> > preceding loop finished, i.e. to a pfn that doesn't actually participate> > in the operation. Shouldn't it be moved inside the loop?>> i removed the WARN_ON_ONCE() from x86.git a few days ago, it's lined up> for the next push.>> Ingo>> --------------------->> Subject: x86: fix leak un ioremap_page_range() failure> From: Ingo Molnar <mingo@elte.hu>> Date: Thu Feb 28 14:02:08 CET 2008>> Jan Beulich noticed that if a driver's ioremap() fails (say due to -ENOMEM)> then we might leak the struct vm_area - free it properly.>> Signed-off-by: Ingo Molnar <mingo@elte.hu>> ---> arch/x86/mm/ioremap.c | 2 +-> 1 file changed, 1 insertion(+), 1 deletion(-)>> Index: linux-x86.q/arch/x86/mm/ioremap.c> ===================================================================> --- linux-x86.q.orig/arch/x86/mm/ioremap.c> +++ linux-x86.q/arch/x86/mm/ioremap.c> @@ -179,7 +179,7 @@ static void __iomem *__ioremap(unsigned> area->phys_addr = phys_addr;> vaddr = (unsigned long) area->addr;> if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot)) {> -	remove_vm_area((void *)(vaddr & PAGE_MASK));> +	free_vm_area(area);> return NULL;> }>> ------------------->> Subject: x86: ioremap(), extend check to all RAM pages> From: Ingo Molnar <mingo@elte.hu>> Date: Thu Feb 28 14:10:49 CET 2008>> Signed-off-by: Ingo Molnar <mingo@elte.hu>> ---> arch/x86/mm/ioremap.c | 5 +++--> 1 file changed, 3 insertions(+), 2 deletions(-)>> Index: linux-x86.q/arch/x86/mm/ioremap.c> ===================================================================> --- linux-x86.q.orig/arch/x86/mm/ioremap.c> +++ linux-x86.q/arch/x86/mm/ioremap.c> @@ -146,8 +146,9 @@ static void __iomem *__ioremap(unsigned> /*> * Don't allow anybody to remap normal RAM that we're using..> */> -	for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&> -	(pfn << PAGE_SHIFT) < last_addr; pfn++) {> +	for (pfn = phys_addr >> PAGE_SHIFT;> +	(pfn << PAGE_SHIFT) < last_addr; pfn++) {> +> if (page_is_ram(pfn) && pfn_valid(pfn) &&> !PageReserved(pfn_to_page(pfn)))> return NULL;> --> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in> the body of a message to majordomo@vger.kernel.org> More majordomo info at http://vger.kernel.org/majordomo-info.html> Please read the FAQ at http://www.tux.org/lkml/>--Thanks,Oliver????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m????????????I?