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| author | Xuewen Yan <xuewen.yan@unisoc.com> | 2024-04-22 10:22:38 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-04-22 13:01:27 +0200 |
| commit | 1560d1f6eb6b398bddd80c16676776c0325fe5fe (patch) | |
| tree | 8d730e638bc7b98354c51987b2e2affaec272a07 /kernel/sched/isolation.c | |
| parent | sched/eevdf: Fix miscalculation in reweight_entity() when se is not curr (diff) | |
| download | linux-1560d1f6eb6b398bddd80c16676776c0325fe5fe.tar.xz linux-1560d1f6eb6b398bddd80c16676776c0325fe5fe.zip | |
sched/eevdf: Prevent vlag from going out of bounds in reweight_eevdf()
It was possible to have pick_eevdf() return NULL, which then causes a
NULL-deref. This turned out to be due to entity_eligible() returning
falsely negative because of a s64 multiplcation overflow.
Specifically, reweight_eevdf() computes the vlag without considering
the limit placed upon vlag as update_entity_lag() does, and then the
scaling multiplication (remember that weight is 20bit fixed point) can
overflow. This then leads to the new vruntime being weird which then
causes the above entity_eligible() to go side-ways and claim nothing
is eligible.
Thus limit the range of vlag accordingly.
All this was quite rare, but fatal when it does happen.
Closes: https://lore.kernel.org/all/ZhuYyrh3mweP_Kd8@nz.home/
Closes: https://lore.kernel.org/all/CA+9S74ih+45M_2TPUY_mPPVDhNvyYfy1J1ftSix+KjiTVxg8nw@mail.gmail.com/
Closes: https://lore.kernel.org/lkml/202401301012.2ed95df0-oliver.sang@intel.com/
Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")
Reported-by: Sergei Trofimovich <slyich@gmail.com>
Reported-by: Igor Raits <igor@gooddata.com>
Reported-by: Breno Leitao <leitao@debian.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Reviewed-and-tested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240422082238.5784-1-xuewen.yan@unisoc.com
Diffstat (limited to 'kernel/sched/isolation.c')
0 files changed, 0 insertions, 0 deletions