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b=pa/1Hh267VDif0fGECk4ZBsQQZXzXfS8+im3ufGhSbXqQAUw5hsIrfOzfy1h442s/ leZWhqr9a1qEaoiqvnQ+flJSjdWw3+l2hcccGnCWBNysvlfgxgesGRG0eztr2m27Z5 WFbIAE6/2kpFTBY+s9f0zz7IHcv67IRQ5eSBBJW+hAdlcNtb92GOzS1cyCPk0FzBbx 1TUeRYgSDmgNq8F7wegrNC4MyLjIRII4Bx2xUSOylKEm99RqJ8jyEtUx4zLNhjvq2r vD749FkEGato7zuc9wkEF98Wvaxk35fOtkn+VyN1KBJth4VY00iiizRnFXsNI5bvQu bppMvpKICqtyg== 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 v2 05/10] mm/damon/core: add damon_merge_two_regions() debug_sanity check Date: Sun, 1 Mar 2026 09:43:20 -0800 Message-ID: <20260301174327.76849-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260301174327.76849-1-sj@kernel.org> References: <20260301174327.76849-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: i8t5khym7sikd7owgn4axy783imrq1bf X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 5360D40006 X-HE-Tag: 1772387013-931630 X-HE-Meta: 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 vKVhd+vA PIsTC3eWHoINInmJadl/wCaheXVfISr0ZRULr32gryTxnBL5bbdB2RmNLFOyFDMdN0k+QOkH+9obu4ytY8Ul4Ax+NPYJTCtVpDysoeDIEAPOI1EHQT4JYmGE4nkgc/VkuY+Rwoju3hXJb+FHxavEFVxJA8SPqvuozorpM3UYu7nLyqF1V3WqcLoTbyiGG5pVLilmdKEAWhgJWMx81hj5doyouV3YxMt5zgvBvGsq6WZjTgrsp94tSjIYh7MaUtGsQcwucOWdkYtfnbqu/wXgeojnB5Q== 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 | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 2b5aed89d449d..8a3738a17cdd9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2473,6 +2473,21 @@ 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) +{ + /* damon_merge_two_regions() may created incorrect left region */ + WARN_ONCE(l->ar.start >= l->ar.end, "l: %lu-%lu, r: %lu-%lu\n", + l->ar.start, l->ar.end, r->ar.start, r->ar.end); +} +#else +static void damon_verify_merge_two_regions( + struct damon_region *l, struct damon_region *r) +{ +} +#endif + /* * Merge two adjacent regions into one region */ @@ -2486,6 +2501,7 @@ 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