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b=FMPU0gcc510b8hEOWl8XNJ7KTOiGytz9l+pUedihaHWFRn6uhRrB/gBOKhTWft8Nb KNUV0QEEPs9xlYvEMDvorRwl7OXRGWmjadBvyhj2HyjAYg+m34AYb/u91F9y6diVBO Fzjrqt4+xp+Byx+X+4H+8H2BBPcQaoV93V4PycUJHwCLiS11ZdUDF9L+zFPqhIYFEE n+CsIDT4AAafAisaotM9bYGCa636a5HiGodSMGZUBFfXxfjPoTWrbndQ4rOwuIK3Uh QZE3ET4nfj7taaOxuJr5/xUXacJmh0Tmsp4ODD97FuQsWcv8IzcwsVuvsS1WLDaTKu xbM1VAq6dRolQ== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 02/14] mm/damon/core: do not use region out of a loop in damon_set_regions() Date: Fri, 22 May 2026 08:40:13 -0700 Message-ID: <20260522154026.80546-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260522154026.80546-1-sj@kernel.org> References: <20260522154026.80546-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Stat-Signature: 3d8jqsqnyun1tzwksystqdcr15grq39r X-Rspamd-Queue-Id: 5282AC000D X-Rspam-User: X-HE-Tag: 1779464436-5875 X-HE-Meta: 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 ADP6XdAp NXYNua4ELoiJ/D9a12eEIv3Se6S2bya6HG3ldNxjgWWYdM3o2fnNSAC2D1SAm4W1phY6FYD/ZhPOjyFiu0ijpf4pAVXRfk1mDyiCAlHeW/b/eQ2H3F2jl5r6MX+j6YzdfRGqeLH+q4xvOlJKu62rDnxbLPvBC1qxtjzTMtzt85AvoruDAz5pixyetmLOY3whkN4TIaFqKUGJ8opOKQNZHrUzjpx59Cg4yIbHnnRP9ksVN5g+pcV59ePMOrNj5HxFyQooOmPPrArPBSqB/NgXyi31c8w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: damon_set_regions() assumes the DAMON region iterator is referencing the last region after the region iteration loop is completed. The code is indeed implemented in the way, but that is not a documented safe behavior. Hence it is unreliable and difficult to read. Cleanup the code to avoid the case. No behavioral change is intended. Signed-off-by: SeongJae Park --- mm/damon/core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 40946a7f6f549..e8cf3632115e5 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -374,6 +374,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, for (i = 0; i < nr_ranges; i++) { struct damon_region *first = NULL, *last, *newr; struct damon_addr_range *range; + bool insert_before_r = false; range = &ranges[i]; /* Get the first/last regions intersecting with the range */ @@ -383,8 +384,10 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, first = r; last = r; } - if (r->ar.start >= range->end) + if (r->ar.start >= range->end) { + insert_before_r = true; break; + } } if (!first) { /* no region intersects with this range */ @@ -394,7 +397,11 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, ALIGN(range->end, min_region_sz)); if (!newr) return -ENOMEM; - damon_insert_region(newr, damon_prev_region(r), r, t); + if (insert_before_r) + damon_insert_region(newr, damon_prev_region(r), + r, t); + else + damon_add_region(newr, t); } else { /* resize intersecting regions to fit in this range */ first->ar.start = ALIGN_DOWN(range->start, -- 2.47.3