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| author | Will Deacon <will.deacon@arm.com> | 2012-08-10 17:51:18 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-09-14 10:00:36 -0700 |
| commit | 9a0417a2d4b082bede8c0495d14d8bb20afaa700 (patch) | |
| tree | 283aad49cbeaf79cbfcd021fb7a1417cf7f7a1f2 /arch/arm/include/asm/msgbuf.h | |
| parent | 33fe660ca2679c4d0234a49cffb82001a57ab003 (diff) | |
| download | lwn-9a0417a2d4b082bede8c0495d14d8bb20afaa700.tar.gz lwn-9a0417a2d4b082bede8c0495d14d8bb20afaa700.zip | |
ARM: 7487/1: mm: avoid setting nG bit for user mappings that aren't present
commit 47f1204329237a0f8655f5a9f14a38ac81946ca1 upstream.
Swap entries are encoding in ptes such that !pte_present(pte) and
pte_file(pte). The remaining bits of the descriptor are used to identify
the swapfile and offset within it to the swap entry.
When writing such a pte for a user virtual address, set_pte_at
unconditionally sets the nG bit, which (in the case of LPAE) will
corrupt the swapfile offset and lead to a BUG:
[ 140.494067] swap_free: Unused swap offset entry 000763b4
[ 140.509989] BUG: Bad page map in process rs:main Q:Reg pte:0ec76800 pmd:8f92e003
This patch fixes the problem by only setting the nG bit for user
mappings that are actually present.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm/include/asm/msgbuf.h')
0 files changed, 0 insertions, 0 deletions