From nobody Wed Dec 17 02:53:00 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 266AFC25B42 for ; Sun, 22 Oct 2023 21:07:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232838AbjJVVHp (ORCPT ); Sun, 22 Oct 2023 17:07:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232228AbjJVVHm (ORCPT ); Sun, 22 Oct 2023 17:07:42 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11688E9; Sun, 22 Oct 2023 14:07:41 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33BD1C433CA; Sun, 22 Oct 2023 21:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1698008860; bh=yOdMqP6KZLl0RBsnjmhN2cj6fhQSH3cbP76PBzRCOAg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NnueFOFQ6TdfQk/iuPOF/OFgmETyKyueN3Q8xtoB6EEMbxvxVHfON+yY3CJBuKIRg f1yY9C/RuQcxMRhpnmwPmKVJUrrynqKh1TIniakjnBDBebuy6nXz+TWubn1wXJd8Ri 010+bl5UYfpbCkevNZLOml+RapqIGvkwqzz3lxyAuuzj2AkffQe+/Rs6lpFqe1g/4y vz4FyTcuIiHO78oGe60UG78FqYJFRUiZgnxU8cZURkIctRznFCXHqveGG5bFPIjO9+ 4bX43pRwyubtaSVX4tcbeKdOl2Tu5t2E9xGZMEzJx4bTe0+pC+JyvjamJC/usJ0bld D7ogbirT/qmAg== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 1/2] mm/damon/sysfs: remove requested targets when online-commit inputs Date: Sun, 22 Oct 2023 21:07:33 +0000 Message-Id: <20231022210735.46409-2-sj@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231022210735.46409-1-sj@kernel.org> References: <20231022210735.46409-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. Fixes: da87878010e5 ("mm/damon/sysfs: support online inputs update") Cc: # 5.19.x Signed-off-by: SeongJae Park --- mm/damon/sysfs.c | 50 +++++++++--------------------------------------- 1 file changed, 9 insertions(+), 41 deletions(-) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index f73dc88d2d19..5268e8503722 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1150,58 +1150,26 @@ static int damon_sysfs_add_target(struct damon_sysf= s_target *sys_target, return err; } =20 -/* - * 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 =3D find_get_pid(sys_target->pid); - if (!pid) - return ERR_PTR(-EINVAL); - damon_for_each_target(t, ctx) { - if (t->pid =3D=3D 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; =20 /* Multiple physical address space monitoring targets makes no sense */ if (ctx->ops.id =3D=3D DAMON_OPS_PADDR && sysfs_targets->nr > 1) return -EINVAL; =20 + damon_for_each_target_safe(t, next, ctx) { + if (damon_target_has_pid(ctx)) + put_pid(t->pid); + damon_destroy_target(t); + } + for (i =3D 0; i < sysfs_targets->nr; i++) { struct damon_sysfs_target *st =3D sysfs_targets->targets_arr[i]; - struct damon_target *t =3D damon_sysfs_existing_target(st, ctx); - - if (IS_ERR(t)) - return PTR_ERR(t); - if (!t) - err =3D damon_sysfs_add_target(st, ctx); - else - err =3D damon_sysfs_set_regions(t, st->regions); + + err =3D damon_sysfs_add_target(st, ctx); if (err) return err; } --=20 2.34.1