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authorValentin Schneider <valentin.schneider@arm.com>2021-05-26 21:57:50 +0100
committerPeter Zijlstra <peterz@infradead.org>2021-06-01 16:00:11 +0200
commit475ea6c60279e9f2ddf7e4cf2648cd8ae0608361 (patch)
treed883c9408ae9ec0b7dc52ecdc9b74b7633a5913a /drivers/gpu/drm/i915/gvt/kvmgt.c
parent08f7c2f4d0e9f4283f5796b8168044c034a1bfcb (diff)
downloadlinux-475ea6c60279e9f2ddf7e4cf2648cd8ae0608361.tar.bz2
sched: Don't defer CPU pick to migration_cpu_stop()
Will reported that the 'XXX __migrate_task() can fail' in migration_cpu_stop() can happen, and it *is* sort of a big deal. Looking at it some more, one will note there is a glaring hole in the deferred CPU selection: (w/ CONFIG_CPUSET=n, so that the affinity mask passed via taskset doesn't get AND'd with cpu_online_mask) $ taskset -pc 0-2 $PID # offline CPUs 3-4 $ taskset -pc 3-5 $PID `\ $PID may stay on 0-2 due to the cpumask_any_distribute() picking an offline CPU and __migrate_task() refusing to do anything due to cpu_is_allowed(). set_cpus_allowed_ptr() goes to some length to pick a dest_cpu that matches the right constraints vs affinity and the online/active state of the CPUs. Reuse that instead of discarding it in the affine_move_task() case. Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") Reported-by: Will Deacon <will@kernel.org> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210526205751.842360-2-valentin.schneider@arm.com
Diffstat (limited to 'drivers/gpu/drm/i915/gvt/kvmgt.c')
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