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b=ZLgrWyhwax0cT7nz0xs/EG9v4tu/MXv7OA36zpiRe2CNexw3DJQnjeNnnVtyo4Vxm 4Rkn7BFF5uU6H1th8z0cFPpFFImYeswzF2ASAGdvmkiJEG7rbMYYdogAiu1IWefaXX UvHXjfodd4SRfEWISn9njL7ykKKALl86yVFpDR/kXFZj+ylG7hSQLAo2NVyrxJ7Ib2 sxPu0GkvnKLwbdzMY01yG6zEnhaMBa2HOWq4L75Nrj7kLEfZ/UuLxbnCaPIykfSiCo L2i0Q7TedqgX98EGs6WaO1aGc+xO1zGtnUkM3ovSuNg7OG7SzZmoHpjuARgz95HecE 89GY/aErOPc/g== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 05/10] mm/damon/core: add damon_merge_two_regions() debug_sanity check Date: Sat, 21 Feb 2026 11:36:22 -0800 Message-ID: <20260221193629.19332-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260221193629.19332-1-sj@kernel.org> References: <20260221193629.19332-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: dmeodmo5ucjqxowpktf7gd1fh1sptk4q X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E82D140004 X-HE-Tag: 1771702596-473372 X-HE-Meta: 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 21JYtWwi 1acl4Vnp4JT1lhqCb8JKFLf5cq84IkpGEpMNEBkt52lwvwcUO2hLRTu+nYnyMYmYqunykDkeElf0wUjI69Xb/UlPoDcea0B0ThGHCOF+yI/3LcdEJ6a7SzIjEEarXquwjlY/9phDzb4Y0vxAXibTN9qrgMHCmpKjvB8z3BsM0MqgkrFofGP/TmkmirO4xEyqzznF7lg51cxpqf7lvxgQb88AUd837rv5DXtCf0Lg0LQu1uN6IgiyWeAes8ZcmxjkjIH5+dmory1Zb0G2Y2tIXqfC5DQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: A data corruption could cause damon_merge_two_regions() creating zero length DAMON regions. Add a sanity check for that under CONFIG_DAMON_DEBUG_SANITY. Signed-off-by: SeongJae Park --- mm/damon/core.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index ede76e0789be3..291a847a8c9bb 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2507,6 +2507,25 @@ static void kdamond_apply_schemes(struct damon_ctx *c) mutex_unlock(&c->walk_control_lock); } +#ifdef CONFIG_DAMON_DEBUG_SANITY +static void damon_verify_merge_two_regions( + struct damon_region *l, struct damon_region *r) +{ + if (l->ar.start < l->ar.end) + return; + + pr_err("damn_merge_two_regions() created incorrect left region\n"); + pr_err("l: %lu-%lu, r: %lu-%lu\n", + l->ar.start, l->ar.end, r->ar.start, r->ar.end); + WARN_ONCE(); +} +#else +static void damon_verify_merge_two_regions( + struct damon_region *l, struct damon_region *r) +{ +} +#endif + /* * Merge two adjacent regions into one region */ @@ -2520,6 +2539,9 @@ static void damon_merge_two_regions(struct damon_target *t, l->nr_accesses_bp = l->nr_accesses * 10000; l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r); l->ar.end = r->ar.end; + + damon_verify_merge_two_regions(l, r); + damon_destroy_region(r, t); } -- 2.47.3