From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 254A340DFD8; Sun, 22 Mar 2026 00:37:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774139849; cv=none; b=bIAQKoxTl6j9HssLBWEhiiitBHIVegEWH24nBvyx2VqoJYqikk3yCmBBSda6OoY4iY8+eJRkULpt5kEvxvNeLKGdJVrswWawQ6qNHX0qpZAYMdDMZF+Oc/3opGsZkWccfyr0oETI56F/xbkBXiU6i9O0XwnNIlM74uKgoWQCYLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774139849; c=relaxed/simple; bh=89fGsGWfw5adeU2D1DKTxKln2906eiVwM5FfbSShElI=; h=Date:To:From:Subject:Message-Id; b=RE+QeZ3fOK2bYAOXHR6dhQsUpNjz30gx6VXnGjq9Dw6WgpgxauHfFSTIpeJ8oemaH0nW67yWlWgZVf/jDKdwSD6Tw3acpFgpleWoGC/aEuUaBY5ph+GZo1pyUuiniQVWmtAGFUIV976jJ7XW3GPv/92YE8T5LU+KdeyWvn8Kqp8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=Gxz/ixYn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="Gxz/ixYn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0086C19421; Sun, 22 Mar 2026 00:37:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1774139848; bh=89fGsGWfw5adeU2D1DKTxKln2906eiVwM5FfbSShElI=; h=Date:To:From:Subject:From; b=Gxz/ixYnd/DOnEwRRccUv3GmwoeAJzHESZ0WLrVBLVbYZMHvXAYmGX2mItQUYN7ed qyDNPKTbgWIZ4bwalU9gdzOBoRWsTSD0V+QovUPeh/+u30oPRStJPwW64973AmdNYY 0LX46pdq3Y76AMq1Ae31X7j9S06/4krzdGSw7WfM= Date: Sat, 21 Mar 2026 17:37:28 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,sj@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-damon-core-avoid-use-of-half-online-committed-context.patch removed from -mm tree Message-Id: <20260322003728.A0086C19421@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/damon/core: avoid use of half-online-committed context has been removed from the -mm tree. Its filename was mm-damon-core-avoid-use-of-half-online-committed-context.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: SeongJae Park Subject: mm/damon/core: avoid use of half-online-committed context Date: Thu, 19 Mar 2026 07:52:17 -0700 One major usage of damon_call() is online DAMON parameters update. It is done by calling damon_commit_ctx() inside the damon_call() callback function. damon_commit_ctx() can fail for two reasons: 1) invalid parameters and 2) internal memory allocation failures. In case of failures, the damon_ctx that attempted to be updated (commit destination) can be partially updated (or, corrupted from a perspective), and therefore shouldn't be used anymore. The function only ensures the damon_ctx object can safely deallocated using damon_destroy_ctx(). The API callers are, however, calling damon_commit_ctx() only after asserting the parameters are valid, to avoid damon_commit_ctx() fails due to invalid input parameters. But it can still theoretically fail if the internal memory allocation fails. In the case, DAMON may run with the partially updated damon_ctx. This can result in unexpected behaviors including even NULL pointer dereference in case of damos_commit_dests() failure [1]. Such allocation failure is arguably too small to fail, so the real world impact would be rare. But, given the bad consequence, this needs to be fixed. Avoid such partially-committed (maybe-corrupted) damon_ctx use by saving the damon_commit_ctx() failure on the damon_ctx object. For this, introduce damon_ctx->maybe_corrupted field. damon_commit_ctx() sets it when it is failed. kdamond_call() checks if the field is set after each damon_call_control->fn() is executed. If it is set, ignore remaining callback requests and return. All kdamond_call() callers including kdamond_fn() also check the maybe_corrupted field right after kdamond_call() invocations. If the field is set, break the kdamond_fn() main loop so that DAMON sill doesn't use the context that might be corrupted. [sj@kernel.org: let kdamond_call() with cancel regardless of maybe_corrupted] Link: https://lkml.kernel.org/r/20260320031553.2479-1-sj@kernel.org Link: https://sashiko.dev/#/patchset/20260319145218.86197-1-sj%40kernel.org Link: https://lkml.kernel.org/r/20260319145218.86197-1-sj@kernel.org Link: https://lore.kernel.org/20260319043309.97966-1-sj@kernel.org [1] Fixes: 3301f1861d34 ("mm/damon/sysfs: handle commit command using damon_call()") Signed-off-by: SeongJae Park Cc: [6.15+] Signed-off-by: Andrew Morton --- include/linux/damon.h | 6 ++++++ mm/damon/core.c | 8 ++++++++ 2 files changed, 14 insertions(+) --- a/include/linux/damon.h~mm-damon-core-avoid-use-of-half-online-committed-context +++ a/include/linux/damon.h @@ -810,6 +810,12 @@ struct damon_ctx { struct damos_walk_control *walk_control; struct mutex walk_control_lock; + /* + * indicate if this may be corrupted. Currentonly this is set only for + * damon_commit_ctx() failure. + */ + bool maybe_corrupted; + /* Working thread of the given DAMON context */ struct task_struct *kdamond; /* Protects @kdamond field access */ --- a/mm/damon/core.c~mm-damon-core-avoid-use-of-half-online-committed-context +++ a/mm/damon/core.c @@ -1252,6 +1252,7 @@ int damon_commit_ctx(struct damon_ctx *d { int err; + dst->maybe_corrupted = true; if (!is_power_of_2(src->min_region_sz)) return -EINVAL; @@ -1277,6 +1278,7 @@ int damon_commit_ctx(struct damon_ctx *d dst->addr_unit = src->addr_unit; dst->min_region_sz = src->min_region_sz; + dst->maybe_corrupted = false; return 0; } @@ -2678,6 +2680,8 @@ static void kdamond_call(struct damon_ct complete(&control->completion); else if (control->canceled && control->dealloc_on_cancel) kfree(control); + if (!cancel && ctx->maybe_corrupted) + break; } mutex_lock(&ctx->call_controls_lock); @@ -2707,6 +2711,8 @@ static int kdamond_wait_activation(struc kdamond_usleep(min_wait_time); kdamond_call(ctx, false); + if (ctx->maybe_corrupted) + return -EINVAL; damos_walk_cancel(ctx); } return -EBUSY; @@ -2790,6 +2796,8 @@ static int kdamond_fn(void *data) * kdamond_merge_regions() if possible, to reduce overhead */ kdamond_call(ctx, false); + if (ctx->maybe_corrupted) + break; if (!list_empty(&ctx->schemes)) kdamond_apply_schemes(ctx); else _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-core-set-quota-score-histogram-with-core-filters.patch mm-damon-core-do-non-safe-region-walk-on-kdamond_apply_schemes.patch mm-damon-core-split-regions-for-min_nr_regions.patch mm-damon-vaddr-do-not-split-regions-for-min_nr_regions.patch mm-damon-test-core-kunit-add-damon_apply_min_nr_regions-test.patch mm-damon-add-config_damon_debug_sanity.patch mm-damon-core-add-damon_new_region-debug_sanity-check.patch mm-damon-core-add-damon_del_region-debug_sanity-check.patch mm-damon-core-add-damon_nr_regions-debug_sanity-check.patch mm-damon-core-add-damon_merge_two_regions-debug_sanity-check.patch mm-damon-core-add-damon_merge_regions_of-debug_sanity-check.patch mm-damon-core-add-damon_split_region_at-debug_sanity-check.patch mm-damon-core-add-damon_reset_aggregated-debug_sanity-check.patch mm-damon-tests-kunitconifg-enable-damon_debug_sanity.patch selftests-damon-config-enable-damon_debug_sanity.patch mm-damon-tests-core-kunit-add-a-test-for-damon_commit_ctx.patch docs-mm-damon-design-document-the-power-of-two-limitation-for-addr_unit.patch mm-damon-core-remove-damos_set_next_apply_sis-duplicates.patch mm-damon-core-use-time_before-for-next_apply_sis.patch mm-damon-core-use-time_after_eq-in-kdamond_fn.patch mm-damon-core-use-mult_frac.patch mm-damon-tests-core-kunit-add-a-test-for-damon_is_last_region.patch mm-damon-core-clarify-damon_set_attrs-usages.patch mm-damon-document-non-zero-length-damon_region-assumption.patch docs-admin-guide-mm-damn-lru_sort-fix-intervals-autotune-parameter-name.patch docs-mm-damon-maintainer-profile-use-flexible-review-cadence.patch docs-mm-damon-index-fix-typo-autoamted-automated.patch mm-damon-core-introduce-damos_quota_goal_tuner.patch mm-damon-core-allow-quota-goals-set-zero-effective-size-quota.patch mm-damon-core-introduce-damos_quota_goal_tuner_temporal.patch mm-damon-sysfs-schemes-implement-quotas-goal_tuner-file.patch docs-mm-damon-design-document-the-goal-based-quota-tuner-selections.patch docs-admin-guide-mm-damon-usage-document-goal_tuner-sysfs-file.patch docs-abi-damon-update-for-goal_tuner.patch mm-damon-tests-core-kunit-test-goal_tuner-commit.patch selftests-damon-_damon_sysfs-support-goal_tuner-setup.patch selftests-damon-drgn_dump_damon_status-support-quota-goal_tuner-dumping.patch selftests-damon-sysfspy-test-goal_tuner-commit.patch mm-damon-core-fix-wrong-end-address-assignment-on-walk_system_ram.patch mm-damon-core-support-addr_unit-on-damon_find_biggest_system_ram.patch mm-damon-core-support-addr_unit-on-damon_find_biggest_system_ram-fix.patch mm-damon-core-receive-addr_unit-on-damon_set_region_biggest_system_ram_default.patch mm-damon-core-receive-addr_unit-on-damon_set_region_biggest_system_ram_default-fix.patch mm-damon-reclaim-respect-addr_unit-on-default-monitoring-region-setup.patch mm-damon-lru_sort-respect-addr_unit-on-default-monitoring-region-setup.patch