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b=rjphx54ch07/tjRjFKkF3By6vtvpnEoUncKbAEpNlvByUm0k6NJiK3Av1UQUAvA7/ LneouAJG8afb9GBos2X2/BHT0+7oWwtTWaYdMGOH27C/1vsA8vR5XCj9KCRigfP3Bo 7ad72wYPbbvz18kBhYzdme8W+ABuQfkCcb/v0HGDCCeUNmkyXDIU8/Cwy0Njj9wTV5 Wt1hoamLPijmJsp5rkEo1Cnd2gpQGLnwFJLpr5vW83Y4IneF8pEqWZhH4R0jD5kiZb AtwYwkRHy3ufNQZWQM/Ikvip8S9PgWIOiSxcdZ1uHjRAI4dMhBWDg1s/ormnLgbIwE bLEcc8txhbO6w== From: SeongJae Park To: SeongJae Park Cc: Andrew Morton , Quanmin Yan , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, wangkefeng.wang@huawei.com, zuoze1@huawei.com, Chris Mason Subject: Re: [PATCH v3 11/11] mm/damon: add damon_ctx->min_sz_region Date: Wed, 17 Sep 2025 09:00:41 -0700 Message-Id: <20250917160041.53187-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250828171242.59810-12-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2862940014 X-Stat-Signature: jrinbjqyr8j4xje1p549zmibug4h8trk X-Rspam-User: X-HE-Tag: 1758124846-57376 X-HE-Meta: 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 7ppFTecu I5H4yx+BXGB6wibvevJ/NEHJTG8heiUZbjzyP1vkpPsICpH3aXMEHABKLNK5B1KAqHuhLW1dDb5MO3gtB1O1mX1uEsa0swwOMy450T7/oyT4rZYweV7grtAXxbJ+id1LJKF989ZTBf1GWDmXzRHlu2BXArKIleCrVylEOjF1pGklBjhQNaqHnDBEVHQh5/88rvZ+AlFBTRIhvePuDCMSYuJ2lPkqCtJHUlr2Gbs5HafsZyttf9gzZk3Jo4CQ45LWbT8VrSwFjP+dhs1CLeK/Zr/DbbrnIojgxx1RSfTt8ySPMKMMJrFpj1PjT+Avpw5/vCy1sM0pvQTDe2MM= 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: On Thu, 28 Aug 2025 10:12:42 -0700 SeongJae Park wrote: > From: Quanmin Yan > > Adopting addr_unit would make DAMON_MINREGION 'addr_unit * 4096' > bytes and cause data alignment issues[1]. > > Add damon_ctx->min_sz_region to change DAMON_MIN_REGION from a global > macro value to per-context variable. > > [1] https://lore.kernel.org/all/527714dd-0e33-43ab-bbbd-d89670ba79e7@huawei.com I think I found an issue of this patch. Please refer to the attaching patch for details. This patch is in the mm tree and not yet merged into the mainline. Andrew, could you please add the attached patch as a fixup of this one? Thanks, SJ ==== Attachment 0 (0001-mm-damon-sysfs-set-damon_ctx-min_sz_region-only-for-.patch) ==== >From af4a31405f4d8c4e5b32f7244f0cdcf960dce30f Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Wed, 17 Sep 2025 08:31:54 -0700 Subject: [PATCH] mm/damon/sysfs: set damon_ctx->min_sz_region only for paddr use case damon_ctx->addr_unit is respected only for physical address space monitoring use case. Meanwhile, damon_ctx->min_sz_region is used by the core layer for aligning regions, regardless of whether it is set for physical address space monitoring or virtual address spaces monitoring. And it is set as 'DAMON_MIN_REGION / damon_ctx->addr_unit'. Hence, if user sets ->addr_unit on virtual address spaces monitoring mode, regions can be unexpectedly aligned in min_sz_region only when it is configured for physical address space monitoring. The issue was found from a result of Chris' experiments that thankfully shared with me off-list. Cc: Chris Mason Signed-off-by: SeongJae Park --- mm/damon/sysfs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index fe4e73d0ebbb..883b0d886d68 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1435,7 +1435,10 @@ static int damon_sysfs_apply_inputs(struct damon_ctx *ctx, if (err) return err; ctx->addr_unit = sys_ctx->addr_unit; - ctx->min_sz_region = max(DAMON_MIN_REGION / sys_ctx->addr_unit, 1); + /* addr_unit is respected by only DAMON_OPS_PADDR */ + if (sys_ctx->ops_id == DAMON_OPS_PADDR) + ctx->min_sz_region = max( + DAMON_MIN_REGION / sys_ctx->addr_unit, 1); err = damon_sysfs_set_attrs(ctx, sys_ctx->attrs); if (err) return err; -- 2.39.5