6.6-stable review patch. If anyone has any objections, please let me know.
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From: SeongJae Park sj@kernel.org
commit 19467a950b49432a84bf6dbadbbb17bdf89418b7 upstream.
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.
[sj@kernel.org: fix unnecessary monitoring results removal] Link: https://lkml.kernel.org/r/20231028213353.45397-1-sj@kernel.org 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/damon/sysfs.c | 68 ++++++++++++++++++++++++++++--------------------------- 1 file changed, 35 insertions(+), 33 deletions(-)
--- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1150,58 +1150,60 @@ 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) +static int damon_sysfs_update_target(struct damon_target *target, + struct damon_ctx *ctx, + struct damon_sysfs_target *sys_target) { struct pid *pid; - struct damon_target *t; + struct damon_region *r, *next;
- 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; - } + if (!damon_target_has_pid(ctx)) + return 0;
- /* 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; - } + return -EINVAL; + + /* no change to the target */ + if (pid == target->pid) { + put_pid(pid); + return 0; } - put_pid(pid); - return NULL; + + /* remove old monitoring results and update the target's pid */ + damon_for_each_region_safe(r, next, target) + damon_destroy_region(r, target); + put_pid(target->pid); + target->pid = pid; + return 0; }
static int damon_sysfs_set_targets(struct damon_ctx *ctx, struct damon_sysfs_targets *sysfs_targets) { - int i, err; + struct damon_target *t, *next; + int i = 0, err;
/* Multiple physical address space monitoring targets makes no sense */ if (ctx->ops.id == DAMON_OPS_PADDR && sysfs_targets->nr > 1) return -EINVAL;
- for (i = 0; i < sysfs_targets->nr; i++) { + damon_for_each_target_safe(t, next, ctx) { + if (i < sysfs_targets->nr) { + damon_sysfs_update_target(t, ctx, + sysfs_targets->targets_arr[i]); + } else { + if (damon_target_has_pid(ctx)) + put_pid(t->pid); + damon_destroy_target(t); + } + i++; + } + + for (; 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; }