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([221.156.231.192]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b463cb01afsm48231925ad.25.2026.04.14.03.43.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 03:43:59 -0700 (PDT) From: DaeMyung Kang To: Mike Rapoport , Andrew Morton Cc: Masami Hiramatsu , Steven Rostedt , Donet Tom , stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, DaeMyung Kang Subject: [PATCH v2] mm/memblock: fix off-by-one page leak in reserve_mem_release_by_name() Date: Tue, 14 Apr 2026 19:43:53 +0900 Message-ID: <20260414104353.989063-1-charsyam@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260414094439.982853-1-charsyam@gmail.com> References: <20260414094439.982853-1-charsyam@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" free_reserved_area() treats its 'end' argument as exclusive: it aligns end down via 'end & PAGE_MASK' and iterates with 'pos < end'. reserve_mem_release_by_name() instead passes 'start + map->size - 1', which causes the last page of a page-aligned reservation to never be freed. For a reservation spanning N pages, only N - 1 pages are released back to the allocator. Fix it by passing the exclusive end address, 'start + map->size'. Fixes: 74e2498ccf7b ("mm/memblock: Add reserved memory release function") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Reviewed-by: Donet Tom donettom@linux.ibm.com --- Changes in v2: - Add Fixes: tag and Cc: stable (per Donet Tom's review). - v1: https://lore.kernel.org/lkml/ mm/memblock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memblock.c b/mm/memblock.c index b3ddfdec7a80..d4a02f1750e9 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2434,7 +2434,7 @@ int reserve_mem_release_by_name(const char *name) return 0; =20 start =3D phys_to_virt(map->start); - end =3D start + map->size - 1; + end =3D start + map->size; snprintf(buf, sizeof(buf), "reserve_mem:%s", name); free_reserved_area(start, end, 0, buf); map->size =3D 0; --=20 2.43.0