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b=erX6JcxZmIcrZHCAP2aqWFKZfJeXTO2GXWNjtqNyT3fI4ae3SFvQ+uj/xwBiSLWEm 0XXbMJrQmYdX2XXxmSAZpAmKAEM+hczHm8PLuZDYQipS3uh0sqgKTiLcuenNPV0SDG KoV4yZGT6yb+sW6dwdzWh/pApVzsqvkOzR3F2y9BFXjzRlybBVrxzm0Rc7r3XAk0ff 7zQQ+tnPRKcvBgnyR62eqIFoUkJ0Hm8PcpBg43sJJTjkbRaYSz3JTs5Ogo4L425H8d eIg0dyf4aJAnl/h4HfnEGY9yXmrV9v0i1NM47T3Hctkq1qF5cpJAEwFpCDlfhH2XBE n9XUCvNAnVceg== From: SeongJae Park To: Zenghui Yu Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, wangzhigang17@huawei.com, liqiqi23@huawei.com, stable@vger.kernel.org Subject: Re: [PATCH v2] samples/damon/mtier: fail early if address range parameters are invalid Date: Tue, 9 Jun 2026 07:49:17 -0700 Message-ID: <20260609144918.69429-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260609064653.1829-1-yuzenghui@huawei.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: te5mk4pcq8ohqtdd4tbsuwb6ahhqktmy X-Rspamd-Queue-Id: 94A838001A X-HE-Tag: 1781016568-618071 X-HE-Meta: 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 SFztBRz/ u6+JEFJwBKlrEwDdnnjPwsIxlZnAXORoyrIMzQz6XkCe6SDw7RsDrOIgud3K24AKhwyCNERX1Q5VkuXRE5BcQ117f95bwwvZneg7WoJ8er+Px1ef7gZB/UlC9hFEl0Ev6B9G1QUY4GGSq8XOu4auV0FrJRn8xy4Me2Ym8kE+ls3Sd8wXDAM+W8G/R0mrdPofATcgJHQIjQZCcn3Fjg4d2rEyqUYxkIGXXkIXqhnKdg1nt8tEicOXs+a73bPMZSa5+bz+eBOEC1/q5jZ8cnywzk1KSIQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 9 Jun 2026 14:46:52 +0800 Zenghui Yu wrote: > The comment on top of `struct damon_region` clearly says that > > For any use case, @ar should be non-zero positive size. > > which is now verified in damon_verify_new_region() if the kernel is built > with DAMON_DEBUG_SANITY. > > The WARN_ONCE() can be triggered if the mtier sample module is enabled > before node{0,1}_{start,end}_addr have been properly initialized, which is > obviously not good. > > ------------[ cut here ]------------ > start 0 >= end 0 > WARNING: mm/damon/core.c:217 at damon_new_region+0xf4/0x118, CPU#59: bash/341468 > Call trace: > damon_new_region+0xf4/0x118 (P) > damon_set_regions+0xfc/0x3c0 > damon_sample_mtier_build_ctx+0xe8/0x3a8 > damon_sample_mtier_start+0x1c/0x90 > damon_sample_mtier_enable_store+0x98/0xb0 > param_attr_store+0xb4/0x128 > module_attr_store+0x2c/0x50 > sysfs_kf_write+0x58/0x90 > kernfs_fop_write_iter+0x16c/0x238 > vfs_write+0x2c0/0x370 > ksys_write+0x74/0x118 > __arm64_sys_write+0x24/0x38 > invoke_syscall+0xa8/0x118 > el0_svc_common.constprop.0+0x48/0xf0 > do_el0_svc+0x24/0x38 > el0_svc+0x54/0x370 > el0t_64_sync_handler+0xa0/0xe8 > el0t_64_sync+0x1ac/0x1b0 > ---[ end trace 0000000000000000 ]--- > > Note that the same issue can happen if detect_node_addresses is true, and > node 0 or 1 is memoryless. Fix it together by checking the validity of > parameters right before damon_new_region() and fail early if they're > invalid. Thank you for this patch, Zenghui! > > Signed-off-by: Zenghui Yu I think this deserves Fixes: and Cc: stable, like below. Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Cc: # 6.16.x Other than that, looks good to me. Reviewed-by: SeongJae Park I applied this patch to damon/next [1] tree. We are now quite close to next merge window. We (mm community) want to focus on making mm.git more stabilized and therefore ready for the next merge window, rather than adding more changes that are not really urgent. I understand this series is not really urgent, because it is causing only DAMON internal weird behavior and one time warning on debug kernels. Hence, Andrew might not add this patch until next -rc1 release. In the case, I will request adding this to mm.git after next -rc1 release. So, no action from your side is needed for now. Let me know if you think this is really urgent or I'm missing something. [1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees Thanks, SJ [...]