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Date: Sat, 4 Jan 2014 15:52:14 -0500 (EST) From: Mikulas Patocka <mpatocka@...hat.com> To: John David Anglin <dave.anglin@...l.net> cc: Joonsoo Kim <iamjoonsoo.kim@....com>, Andi Kleen <ak@...ux.intel.com>, Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@....fi>, linux-kernel@...r.kernel.org, linux-parisc@...r.kernel.org Subject: Re: [PATCH] fix crash when using XFS on loopback On Sat, 4 Jan 2014, John David Anglin wrote: > On 4-Jan-14, at 2:55 PM, Mikulas Patocka wrote: > > > On Sat, 4 Jan 2014, John David Anglin wrote: > > > > > On 4-Jan-14, at 12:45 PM, Mikulas Patocka wrote: > > > > > > > * flush_dcache_page asks for the list of userspace mappings, however > > > > that > > > > page->mapping field is reused by the slab subsystem for a different > > > > purpose. This causes the crash. > > > > > > I'd noticed the other day that the parisc implementation of > > > flush_dcache_page() > > > should return if "!mapping || mapping != page->mapping" is true. This > > > would > > > have avoided crash. > > > > > > Dave > > > > I think no. > > > > page_mapping returns NULL if the page has only anonymous mapping and it is > > not placed in the swap cache. In this case, you need to flush the kernel > > cache. > > > The suggestion is to add the "mapping != page->mapping" to the current NULL > check. > It occurs after the kernel cache flush. "if (!mapping || mapping != page->mapping) return;" returns if the mapping is NULL (and that is wrong because the variable mapping is NULL for anonymous pages). You could probably return "if (!mapping && !PageAnon(page))", but the other architectures aren't doing it. > It doesn't seem right to flush the vma mappings associated with swap address > space > and that appears to be happening with current code. > > Dave > -- > John David Anglin dave.anglin@...l.net I suppose that "vma_interval_tree_foreach" is empty operation for swap address space. Or isn't it? Mikulas -- 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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