From: Xiao Liang <shaw.leon@gmail.com> stable inclusion from stable-v5.10.246 commit 3c1cb53236a12a3374365990eccfff5336aa63df category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ID3Y90 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 501302d5cee0d8e8ec2c4a5919c37e0df9abc99b ] 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: 6fc4dbcf0276 ("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> [ moved from padata_reorder() local variables to padata_find_next() using pd->processed and pd->cpu struct members ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Wang Tao <wangtao554@huawei.com> --- kernel/padata.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/padata.c b/kernel/padata.c index d0f6bf1cf18a..a93a269045da 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -295,7 +295,11 @@ 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); -- 2.34.1