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b=beJzbYhbsUaFJb+iBlNUq5lBMdl2PkZuSguZb8itkZ/vO+zcHB7u2Jg3vKgPyepG0 x0+NRQl6zljrn9j9YL4H6oMewiET+NhzPGYg2H9dYsBT0lQs5aAbD83LTVhOgFeHz3 U1lL/isFBX+L+wPGxhqX3NjLosS3mTD3+o+pR6L1FExVAi1oKQ+L09TP5DPsO/VJJR qJEYbP26knXKRATUJfdKx2WeYnHOIVTeIJH47vpLRLjl0CSk1SYEuElBHic+2oJsYC 9uG0DcEXvmhgNNfsTOaeeYaM42VOe/xQwPKPxf9kMP5fdwzT5KoJiGA7BhmwKcevhm ydrClkokl5rfQ== From: SJ Park To: Arnd Bergmann Cc: SJ Park , Andrew Morton , Nathan Chancellor , Arnd Bergmann , Nick Desaulniers , Bill Wendling , Justin Stitt , Ravi Jonnalagadda , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH] damon: reduce stack usage further Date: Fri, 25 Sep 2026 12:01:43 -0700 Message-ID: <20260925190143.2553-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260925130254.4022227-1-arnd@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 1F8E5C000E X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: ffq1oj9t483nxmx4beh4x17r9xo4cm95 X-HE-Tag: 1790362911-932848 X-HE-Meta: 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 YwYeLb6m pqDAtSktJzrPKhHfEqpFCc3liIhayuvXDxg1necDGH9brq2IHDDovu7wNx69oK339DJ+KgWf0L8qHCsIdRSnqrcgWNb9kRCuVlRlk3KiNaZFsAlNfzhya4IG9bpWAIg3VEJAdSn1cPUpmVl8u3gYknk4g7Q3JiW9l5WBZCXt5SCZLl6hakIqxQ6efkFj/qpenGolJFoQrT/7JNOzKISbTAa/t7Viw6XqISbWzwOIvKFTbSN0fjISxINAoD90DmyV+ufbXUetWqY9Qp6rB9yfWkR39TfgweRXqWslfx+LCCd8CGYybnbiPWzaA1RoWB8lL4ueqvo/ztPNVIAM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 25 Sep 2026 15:02:46 +0200 Arnd Bergmann wrote: > From: Arnd Bergmann > > In a previous patch, I had annotated kdamond_tune_intervals() as > noinline_for_stack in order to not exceed the stack frame warning > limit. Unfortunately, my current linux-next randconfig builds show > a similar problem again with clang-21: > > mm/damon/core.c:3953:12: error: stack frame size (1288) exceeds limit (1280) in 'kdamond_fn' [-Werror,-Wframe-larger-than] > 3953 | static int kdamond_fn(void *data) > > Do the same thing with kdamond_apply_schemes(), kdamond_merge_regions(), > and kdamond_split_regions(), which also have individually large stacks. > This should work to keep the deepest total stack depth down much more > as well as avoid the warning. > > I also tried to reduce the complexity of kdamond_fn() itself by splitting > out the while() loop into a separate function. While this arguably led > to slightly more readable code, it had no effect on the total stack > usage and just made the new function the largest stack user and had > a nonzero risk of me getting the conversion wrong. Looks good to me. Thank you Arnd! > > Fixes: 5a00cae64de1 ("mm/damon/core: reduce kernel stack usage") > Signed-off-by: Arnd Bergmann Reviewed-by: SJ Park This patch is applied to damon/next [1] tree. If this patch is not added to mm.git in short term (~1 week?), I will ask mm.git maintainer (Andrew Morton) to pick this. So, no action from your side is needed for now. If it seems I also forgot doing that or you cannot wait for my action, please feel free to ping me or Andrew. [1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees Thanks, SJ [...]