Re: [PATCH mm-hotfixes-unstable 2/3] mm/damon/tests/sysfs-kunit: fix leaked pid reference in add_targets test

[sashiko-bot@kernel.org]

> From: Wang Xiaolei <xiaoleiwangxiaolei@gmail.com>
> 
> damon_sysfs_test_add_targets() creates its monitoring context with
> damon_new_ctx(), which leaves ctx->ops zero-initialized.  Since
> DAMON_OPS_VADDR is zero, damon_target_has_pid() returns true for the
> context, and damon_sysfs_add_targets() therefore calls
> damon_set_target_pid() for each target it adds.  That function grabs a
> reference to the target's struct pid via find_get_pid().
> 
> The test then tears the context down with damon_destroy_ctx(), which
> releases such a reference from ctx->ops.cleanup_target().  For the vaddr
> operations set that callback is damon_va_cleanup_target(), and it is the
> only place where the reference is put.  The test never selects an
> operations set, though, so cleanup_target is NULL and both references --
> one for each of the two damon_sysfs_add_targets() calls -- are leaked on
> [ ... ]
> Cc: Vlastimil Babka <vbabka@kernel.org>
> Cc: "Liam R. Howlett" <liam@infradead.org>
> Signed-off-by: Wang Xiaolei <xiaoleiwangxiaolei@gmail.com>
> Reviewed-by: SJ Park <sj@kernel.org>
> Signed-off-by: SJ Park <sj@kernel.org>

Sashiko has reviewed this patch and found no issues.

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