The patch titled Subject: mm/damon/sysfs: remove requested targets when online-commit inputs has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon/sysfs: remove requested targets when online-commit inputs Date: Sun, 22 Oct 2023 21:07:33 +0000

damon_sysfs_set_targets(), which updates the targets of the context for online commitment, do not remove targets that removed from the corresponding sysfs files. As a result, more than intended targets of the context can exist and hence consume memory and monitoring CPU resource more than expected.

Fix it by removing all targets of the context and fill up again using the user input. This could cause unnecessary memory dealloc and realloc operations, but this is not a hot code path. Also, note that damon_target is stateless, and hence no data is lost.

Link: https://lkml.kernel.org/r/20231022210735.46409-2-sj@kernel.org Fixes: da87878010e5 ("mm/damon/sysfs: support online inputs update") Signed-off-by: SeongJae Park sj@kernel.org Cc: Brendan Higgins brendanhiggins@google.com Cc: stable@vger.kernel.org [5.19.x] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/damon/sysfs.c | 48 +++++++-------------------------------------- 1 file changed, 8 insertions(+), 40 deletions(-)

--- a/mm/damon/sysfs.c~mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs +++ a/mm/damon/sysfs.c @@ -1150,58 +1150,26 @@ destroy_targets_out: return err; }

-/* - * Search a target in a context that corresponds to the sysfs target input. - * - * Return: pointer to the target if found, NULL if not found, or negative - * error code if the search failed. - */ -static struct damon_target *damon_sysfs_existing_target( - struct damon_sysfs_target *sys_target, struct damon_ctx *ctx) -{ - struct pid *pid; - struct damon_target *t; - - if (!damon_target_has_pid(ctx)) { - /* Up to only one target for paddr could exist */ - damon_for_each_target(t, ctx) - return t; - return NULL; - } - - /* ops.id should be DAMON_OPS_VADDR or DAMON_OPS_FVADDR */ - pid = find_get_pid(sys_target->pid); - if (!pid) - return ERR_PTR(-EINVAL); - damon_for_each_target(t, ctx) { - if (t->pid == pid) { - put_pid(pid); - return t; - } - } - put_pid(pid); - return NULL; -} - static int damon_sysfs_set_targets(struct damon_ctx *ctx, struct damon_sysfs_targets *sysfs_targets) { + struct damon_target *t, *next; int i, err;

/* Multiple physical address space monitoring targets makes no sense */ if (ctx->ops.id == DAMON_OPS_PADDR && sysfs_targets->nr > 1) return -EINVAL;

+ damon_for_each_target_safe(t, next, ctx) { + if (damon_target_has_pid(ctx)) + put_pid(t->pid); + damon_destroy_target(t); + } + for (i = 0; i < sysfs_targets->nr; i++) { struct damon_sysfs_target *st = sysfs_targets->targets_arr[i]; - struct damon_target *t = damon_sysfs_existing_target(st, ctx);

- if (IS_ERR(t)) - return PTR_ERR(t); - if (!t) - err = damon_sysfs_add_target(st, ctx); - else - err = damon_sysfs_set_regions(t, st->regions); + err = damon_sysfs_add_target(st, ctx); if (err) return err; } _

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

mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch mm-damon-ops-common-avoid-divide-by-zero-during-region-hotness-calculation.patch mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs.patch mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation.patch mm-damon-sysfs-test-add-a-unit-test-for-damon_sysfs_set_targets.patch