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authorLinus Torvalds <torvalds@linux-foundation.org>2010-08-14 11:44:56 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-20 11:55:38 -0700
commit16af977da0867b1f9fdc98fb61f10ef85a7b60e7 (patch)
tree6ae385b5479335351737ee7e11113e87ab53c80e /mm/mlock.c
parentf6b0f3c69141a21f12cb2f678b0cdaa2be8076a7 (diff)
downloadlinux-2.6.34-ux500-16af977da0867b1f9fdc98fb61f10ef85a7b60e7.tar.gz
mm: fix page table unmap for stack guard page properly
commit 11ac552477e32835cb6970bf0a70c210807f5673 upstream. We do in fact need to unmap the page table _before_ doing the whole stack guard page logic, because if it is needed (mainly 32-bit x86 with PAE and CONFIG_HIGHPTE, but other architectures may use it too) then it will do a kmap_atomic/kunmap_atomic. And those kmaps will create an atomic region that we cannot do allocations in. However, the whole stack expand code will need to do anon_vma_prepare() and vma_lock_anon_vma() and they cannot do that in an atomic region. Now, a better model might actually be to do the anon_vma_prepare() when _creating_ a VM_GROWSDOWN segment, and not have to worry about any of this at page fault time. But in the meantime, this is the straightforward fix for the issue. See https://bugzilla.kernel.org/show_bug.cgi?id=16588 for details. Reported-by: Wylda <wylda@volny.cz> Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Reported-by: Mike Pagano <mpagano@gentoo.org> Reported-by: Fran├žois Valenduc <francois.valenduc@tvcablenet.be> Tested-by: Ed Tomlinson <edt@aei.ca> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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