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authorHeiko Carstens <heiko.carstens@de.ibm.com>2019-11-18 09:38:37 +0100
committerVasily Gorbik <gor@linux.ibm.com>2019-11-30 10:52:44 +0100
commit5a5525b0488ce31e19065f8527dbf50266b5b712 (patch)
tree962f0b570a299c36ea29f9dd2cb14943b488ca68 /mm/backing-dev.c
parenta2308c11ecbc3471ebb7435ee8075815b1502ef0 (diff)
downloadlinux-5a5525b0488ce31e19065f8527dbf50266b5b712.tar.gz
s390/vdso: fix getcpu
getcpu reads the required values for cpu and node with two
instructions. This might lead to an inconsistent result if user space
gets preempted and migrated to a different CPU between the two
instructions.

Fix this by using just a single instruction to read both values at
once.

This is currently rather a theoretical bug, since there is no real
NUMA support available (except for NUMA emulation).

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'mm/backing-dev.c')
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