From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9729F188596; Wed, 15 Jul 2026 04:45:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784090733; cv=none; b=D5skIixvVn5esoQA2gsiCb3O7gnfxKOELxciBZWJIXZIPcXFqK11N99ixRBVtPILCjJ9P3wgJC4pPegO7dV2fPslABiGkiUU80o9bNA3lQDBYGmKjWz8w/EImij7EDcL+pr12XBitpFMm2oBYtFcxkmLcIGp49EG8vUomjRQUeQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784090733; c=relaxed/simple; bh=r3S4QHQd3VaTSbQncAc0/PibyxIV6anaRIOMCk9Cb30=; h=Date:To:From:Subject:Message-Id; b=Ai4ytxRJWHY24B4azKtj93lHVdDKCWFPUxtMhPMqshq5CPY+RcfJFFxljlQGG/ptInNo9z+WVca1O3ubiWF37562i/SIUkJx+j165EjX/cUT8TK/UCsoX/zRrZAU+j1YUY4+JEF4wr2l3pu62m0Rl0Z/O3m/rACDbPXOC1DnQds= 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=B81GDhyr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="B81GDhyr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28ADB1F000E9; Wed, 15 Jul 2026 04:45:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1784090731; bh=ude42ZCbR20/X7z5bIUrcIH0rUqjEMzlc5zkc7ZUOYQ=; h=Date:To:From:Subject; b=B81GDhyrwyqTUo49kT09rjttjuK/ea7nvhyNLeerU2ufGxYEv9VbLgWRnutih2w9v gH6ffWklHbSt31gDQ8vO1uUVVXihMQlmssY1zoKQo3ZANdzg5d1fqo0YhCRDpMvUfN UnTauKkJeK4DYEX4kgb5RPvPZ2pXf+sNOuJRbcSE= Date: Tue, 14 Jul 2026 21:45:30 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,sj@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch added to mm-new branch Message-Id: <20260715044531.28ADB1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/damon/sysfs: read ops_id only once in damon_sysfs_apply_inputs() has been added to the -mm mm-new branch. Its filename is mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: SJ Park Subject: mm/damon/sysfs: read ops_id only once in damon_sysfs_apply_inputs() Date: Tue, 14 Jul 2026 20:10:01 -0700 damon_sysfs_apply_inputs() reads ops_id twice. It could race with ops_id_store(). As a result, the min_region_sz could wrongly be set up. Read it once. The user impact is trivial. Sane users ain't update the parameter in parallel. Even if it happens, the DAMON core layer handles the wrong min_region_sz (!is_power_of_2()). Even if somehow the race ended up making a min_region_sz that is different from the user's intention but still valid, only monitoring itself runs differently than expected. No critical consequences like kernel panic or memory corruption happen The issue was discovered [1] by Sashiko. Link: https://lore.kernel.org/20260715031002.108504-7-sj@kernel.org Link: https://lore.kernel.org/20260703172417.95426-1-sj@kernel.org [1] Fixes: 8d009da32f13 ("mm/damon/sysfs: set damon_ctx->min_sz_region only for paddr use case") Signed-off-by: SJ Park Cc: # 6.18.x Signed-off-by: Andrew Morton --- mm/damon/sysfs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/damon/sysfs.c~mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs +++ a/mm/damon/sysfs.c @@ -2094,14 +2094,16 @@ static inline bool damon_sysfs_kdamond_r static int damon_sysfs_apply_inputs(struct damon_ctx *ctx, struct damon_sysfs_context *sys_ctx) { + enum damon_ops_id ops_id; int err; - err = damon_select_ops(ctx, sys_ctx->ops_id); + ops_id = READ_ONCE(sys_ctx->ops_id); + err = damon_select_ops(ctx, ops_id); if (err) return err; ctx->addr_unit = READ_ONCE(sys_ctx->addr_unit); /* addr_unit is respected by only DAMON_OPS_PADDR */ - if (sys_ctx->ops_id == DAMON_OPS_PADDR) + if (ops_id == DAMON_OPS_PADDR) ctx->min_region_sz = max( DAMON_MIN_REGION_SZ / ctx->addr_unit, 1); ctx->pause = sys_ctx->pause; _ Patches currently in -mm which might be from sj@kernel.org are samples-damon-wsse-handle-damon_start-failure.patch samples-damon-prcl-handle-damon_start-failure.patch samples-damon-mtier-handle-damon_start-failure.patch samples-damon-mtier-handle-damon_stop-failure.patch samples-damon-wsse-stop-and-free-damon-ctx-when-damon_call-fails.patch samples-damon-prcl-stop-and-free-damon-ctx-when-damon_call-fails.patch mm-damon-sysfs-kobject_del-target-normal-context-and-kdamond-dirs.patch mm-damon-sysfs-kobject_del-region-and-target-error-dirs.patch mm-damon-sysfs-schemes-kobject_del-scheme-dirs.patch mm-damon-sysfs-schemes-kobject_del-scheme-region-dirs.patch mm-damon-sysfs-schemes-kobject_del-scheme-filter-dirs.patch mm-damon-sysfs-schemes-kobject_del-scheme-quota-goal-dirs.patch mm-damon-sysfs-schemes-kobject_del-scheme-action-destination-dirs.patch mm-damon-sysfs-kobject_del-probe-dirs.patch mm-damon-sysfs-kobject_del-probe-filter-dirs.patch mm-damon-sysfs-kobject_del-probe-dirs-in-probes_addd_dir-error-path.patch mm-damon-sysfs-schemes-kobject_del-region-for-populate_region-error.patch docs-mm-damon-design-update-for-damos_quota_node_eligible_mem_bp.patch docs-abi-damon-document-probe-files.patch mm-damon-tests-core-kunit-test-damon_rand.patch selftests-damon-sysfssh-test-multiple-probe-dirs-creation.patch selftests-damon-sysfssh-test-coreops_filters-directories.patch selftests-damon-sysfssh-test-dests-dir.patch selftests-damon-sysfssh-test-all-files-in-quota-goal-dir.patch mm-damon-core-reduce-range-setup-in-damon_commit_target_regions.patch mm-damon-sysfs-split-probe-setup-function-out.patch mm-damon-sysfs-split-out-filters-setup-function.patch mm-damon-sysfs-fix-typos-in-probe_addrm_dirs-s-attr-probe.patch mm-damon-core-introduce-damon_nr_accesses_mvsum.patch mm-damon-tests-core-kunit-test-damon_mvsum.patch mm-damon-core-always-update-last_nr_accesses-for-intervals-change.patch mm-damon-core-handle-unreset-nr_accesses-in-damon_nr_accesses_mvsum.patch mm-damon-core-use-damon_nr_accesses_mvsum-in-__damos_valid_target.patch mm-damon-core-use-damon_nr_accesses_mvsum-for-damos-region-tracing.patch mm-damon-sysfs-schemes-use-damon_nr_accesses_mvsum-for-damo-regions.patch mm-damon-core-remove-damon_warn_fix_nr_accesses_corruption.patch mm-damon-core-remove-damon_verify_reset_aggregated.patch mm-damon-core-remove-damon_verify_merge_regions_of.patch mm-damon-tests-core-kunit-remove-nr_accesses_bp-setup-and-tests.patch selftests-damon-drgn_dump_damon_status-do-not-dump-nr_accesses_bp.patch mm-damon-core-remove-nr_accesses_bp-setups-and-updates.patch mm-damon-core-remove-attrs-param-from-damon_update_region_access_rate.patch mm-damon-paddr-remove-attrs-param-from-__damon_pa_check_access.patch mm-damon-vaddr-remove-attrs-param-from-__damon_va_check_access.patch mm-damon-core-remove-damon_moving_sum-and-its-unit-test.patch mm-damon-core-remove-damon_region-nr_accesses_bp.patch mm-damon-add-damon_region-last_probe_hits.patch mm-damon-core-introduce-damon_probe_hits_mvsum.patch mm-damon-sysfs-schemes-set-probe-hits-as-pseudo-moving-sums.patch mm-damon-core-safely-validate-src-on-damon_commit_ctx.patch mm-damon-core-do-parameter-testing-commit-on-damon_start.patch mm-damon-sysfs-remove-duplicated-commit-input-validity-check.patch mm-damon-reclaim-remove-duplicated-min_region_sz-power-of-2-check.patch mm-damon-lru_sort-remove-duplicated-min_region_sz-power_of_2-check.patch mm-damon-document-region-size-validation-in-damon_set_regions.patch mm-damon-core-remove-start-end-check-in-damon_set_region_system_rams.patch mm-damon-sysfs-remove-region-size-validation.patch mm-damon-core-stop-ctxs-in-damon_start-before-returning-an-error.patch samples-damon-mtier-do-not-stop-first-context-for-damon_start-failure.patch mm-damon-core-make-damon_stop-never-fails.patch mm-damon-sysfs-ignore-damon_stop-return-value.patch mm-damon-reclaaim-ignore-damon_stop-return-value.patch mm-damon-lru_sort-ignore-damon_stop-return-value.patch mm-damon-core-change-damon_stop-return-type-to-void.patch samples-damon-mtier-stop-all-contexts-with-single-damon_stop-call.patch mm-damon-core-wait-ctx-stop-in-damon_call-before-reruning-an-error.patch samples-damon-wsse-do-not-stop-ctx-for-damon_call-failure.patch samples-damon-prcl-do-not-stop-damon-for-damon_call-failure.patch mm-damon-core-remove-comment-and-test-for-nr_to_bp-divide-by-zero.patch mm-damon-core-s-damon_max_nr_accesses-damon_nr_samples_per_aggr.patch mm-damon-core-s-accesses_bp_to_nr_accesses-sample_bp_to_count.patch mm-damon-core-s-nr_accesses_to_accesses_bp-sample_count_to_bp.patch mm-damon-core-s-nr_accesses_for_new_attrs-nr_samples_for_new_attrs.patch mm-damon-core-update-probe-hits-for-new-parameter-commit.patch mm-damon-core-handle-unreset-probe_hits-in-probe_hits_mvsum.patch mm-damon-core-introduce-damon_probe-weight.patch mm-damon-core-ask-apply_probes-ops-callback-to-set-sampling-address.patch mm-damon-paddr-set-samples-in-apply_probes-if-requested.patch mm-damon-core-ask-apply_probe-to-return-max-probe-hits-weighted-sum.patch mm-damon-core-implement-damon_probe_hits_wsum.patch mm-damon-paddr-respect-return_max_wsum.patch mm-damon-core-use-abs_diff-instead-of-abs.patch mm-damon-core-extend-merge-function-to-work-with-probe-hits.patch mm-damon-core-disallow-probe_hits-overflow-on-attrs-only-monitoring.patch mm-damon-core-validate-params-for-probe-hits-weighted-sum-overflow.patch mm-damon-core-disable-access-monitoring-when-probe-weights-are-set.patch mm-damon-core-set-samples-in-apply_probes-if-probe-weights-are-set.patch mm-damon-core-s-max_nr_accesses-max_merge_score-in-kdamond_fn.patch mm-damon-core-get-merge-threshold-from-probe-hits-when-weights-are-set.patch mm-damon-core-implement-damon_has_probe_weight.patch mm-damon-sysfs-implement-probe-weight-file.patch docs-mm-damon-design-document-attrs-only-monitoring.patch docs-admin-guide-mm-damon-usage-document-weight-sysfs-file.patch docs-abi-damon-document-probe-weight-file.patch mm-damon-core-skip-aging-from-repeated-aggressive-merging.patch mm-damon-core-hide-private-damon_region-fields.patch mm-damon-core-hide-private-damon_target-fields.patch mm-damon-core-hide-private-damos_quota_goal-fields.patch mm-damon-core-hide-private-damos_quota-fields.patch mm-damon-core-hide-private-damos_filter-fields.patch mm-damon-core-hide-private-damos-fields.patch mm-damon-core-hide-private-damon_filter-fields.patch mm-damon-core-hide-private-damon_probe-fields.patch mm-damon-sysfs-do-not-directly-access-damon_ctx-ops.patch mm-damon-core-hide-core-private-damon_ctx-fields.patch mm-damon-core-avoid-infinite-kdamond_merge_regions-internal-loop.patch mm-damon-tests-core-kunit-catch-test-failure-in-test_merge_regions_of.patch mm-damon-vaddr-drop-last-same-folio-access-check-optimization.patch mm-damon-paddr-drop-last-same-folio-access-check-reuse-optimization.patch mm-damon-sysfs-read-addr_unit-only-once-in-damon_sysfs_apply_inputs.patch mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch