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padata: Reset next CPU when reorder sequence wraps around

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[ Upstream commit 501302d5ce ]

When seq_nr wraps around, the next reorder job with seq 0 is hashed to
the first CPU in padata_do_serial(). Correspondingly, need reset pd->cpu
to the first one when pd->processed wraps around. Otherwise, if the
number of used CPUs is not a power of 2, padata_find_next() will be
checking a wrong list, hence deadlock.

Fixes: 6fc4dbcf02 ("padata: Replace delayed timer with immediate workqueue in padata_reorder")
Cc: <stable@vger.kernel.org>
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[ relocated fix to padata_find_next() using pd->processed and pd->cpu structure fields ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiao Liang
2025-10-20 11:37:02 -04:00
committed by Greg Kroah-Hartman
parent 88ad39711b
commit fd819637d0
1 changed files with 5 additions and 1 deletions
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6
kernel/padata.c
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@@ -290,7 +290,11 @@ static struct padata_priv *padata_find_next(struct parallel_data *pd,
if (remove_object) {
list_del_init(&padata->list);
++pd->processed;
pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false);
/* When sequence wraps around, reset to the first CPU. */
if (unlikely(pd->processed == 0))
pd->cpu = cpumask_first(pd->cpumask.pcpu);
else
pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false);
}
spin_unlock(&reorder->lock);