The patch titled Subject: mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()' has been added to the -mm tree. Its filename is mm-damon-dbgfs-fix-struct-pid-leaks-in-dbgfs_target_ids_write.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-damon-dbgfs-fix-struct-pid-leak... and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-damon-dbgfs-fix-struct-pid-leak...

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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon/dbgfs: fix 'struct pid' leaks in 'dbgfs_target_ids_write()'

DAMON debugfs interface increases the reference counts of 'struct pid's for targets from the 'target_ids' file write callback ('dbgfs_target_ids_write()'), but decreases the counts only in DAMON monitoring termination callback ('dbgfs_before_terminate()').

Therefore, when 'target_ids' file is repeatedly written without DAMON monitoring start/termination, the reference count is not decreased and therefore memory for the 'struct pid' cannot be freed. This commit fixes this issue by decreasing the reference counts when 'target_ids' is written.

Link: https://lkml.kernel.org/r/20211229124029.23348-1-sj@kernel.org Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") Signed-off-by: SeongJae Park sj@kernel.org Cc: stable@vger.kernel.org [5.15+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/damon/dbgfs.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-fix-struct-pid-leaks-in-dbgfs_target_ids_write +++ a/mm/damon/dbgfs.c @@ -353,6 +353,7 @@ static ssize_t dbgfs_target_ids_write(st const char __user *buf, size_t count, loff_t *ppos) { struct damon_ctx *ctx = file->private_data; + struct damon_target *t, *next_t; bool id_is_pid = true; char *kbuf, *nrs; unsigned long *targets; @@ -397,8 +398,12 @@ static ssize_t dbgfs_target_ids_write(st goto unlock_out; }

- /* remove targets with previously-set primitive */ - damon_set_targets(ctx, NULL, 0); + /* remove previously set targets */ + damon_for_each_target_safe(t, next_t, ctx) { + if (targetid_is_pid(ctx)) + put_pid((struct pid *)t->id); + damon_destroy_target(t); + }

/* Configure the context for the address space type */ if (id_is_pid) _

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-dbgfs-fix-struct-pid-leaks-in-dbgfs_target_ids_write.patch mm-damon-remove-some-no-need-func-definitions-in-damonh-file-fix.patch mm-damon-convert-macro-functions-to-static-inline-functions.patch docs-admin-guide-mm-damon-usage-update-for-scheme-quotas-and-watermarks.patch docs-admin-guide-mm-damon-usage-remove-redundant-information.patch docs-admin-guide-mm-damon-usage-mention-tracepoint-at-the-beginning.patch docs-admin-guide-mm-damon-usage-update-for-kdamond_pid-and-mkrm_contexts.patch mm-damon-remove-a-mistakenly-added-comment-for-a-future-feature.patch mm-damon-schemes-account-scheme-actions-that-successfully-applied.patch mm-damon-schemes-account-how-many-times-quota-limit-has-exceeded.patch mm-damon-reclaim-provide-reclamation-statistics.patch docs-admin-guide-mm-damon-reclaim-document-statistics-parameters.patch mm-damon-dbgfs-support-all-damos-stats.patch docs-admin-guide-mm-damon-usage-update-for-schemes-statistics.patch mm-damon-dbgfs-remove-a-unnecessary-variable.patch mm-damon-vaddr-use-pr_debug-for-damon_va_three_regions-failure-logging.patch mm-damon-vaddr-hide-kernel-pointer-from-damon_va_three_regions-failure-log.patch mm-damon-hide-kernel-pointer-from-tracepoint-event.patch