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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-05-18 20:37:41 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-19 14:48:18 -0400
commitfa9dc265ace9774e62f0e31108e5f47911124bda (patch)
treef5230efca0ccf0cfec7690a6c45209cff938d740 /kernel/cgroup_freezer.c
parentcf77e988ddfc7f047ac1ddc72cadb5eee7e09293 (diff)
cpumask: fix compat getaffinity
Commit a45185d2d "cpumask: convert kernel/compat.c" broke libnuma, which abuses sched_getaffinity to find out NR_CPUS in order to parse /sys/devices/system/node/node*/cpumap. On NUMA systems with less than 32 possibly CPUs, the current compat_sys_sched_getaffinity now returns '4' instead of the actual NR_CPUS/8, which makes libnuma bail out when parsing the cpumap. The libnuma call sched_getaffinity(0, bitmap, 4096) at first. It mean the libnuma expect the return value of sched_getaffinity() is either len argument or NR_CPUS. But it doesn't expect to return nr_cpu_ids. Strictly speaking, userland requirement are 1) Glibc assume the return value mean the lengh of initialized of mask argument. E.g. if sched_getaffinity(1024) return 128, glibc make zero fill rest 896 byte. 2) Libnuma assume the return value can be used to guess NR_CPUS in kernel. It assume len-arg<NR_CPUS makes -EINVAL. But it try len=4096 at first and 4096 is always bigger than NR_CPUS. Then, if we remove strange min_length normalization, we never hit -EINVAL case. sched_getaffinity() already solved this issue. This patch adapts compat_sys_sched_getaffinity() to match the non-compat case. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Arnd Bergmann <arnd@arndb.de> Reported-by: Ken Werner <ken.werner@web.de> Cc: stable@kernel.org Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cgroup_freezer.c')
0 files changed, 0 insertions, 0 deletions