From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7827F3A1AD for ; Tue, 19 Dec 2023 20:51:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="2W2G+JwN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6F4EC433C8; Tue, 19 Dec 2023 20:51:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1703019077; bh=jqu//i63yzu14YXHWaw+wLfgyRHKQeHiWOfkghTser0=; h=Date:To:From:Subject:From; b=2W2G+JwNx1bAUq2tCAL50n8dK/KwFkd88cCI3lukcjGgyVT0XjDcL5sNJAO3SST+Z 6Ka0s4RP3nY9zArLbnWHFmhZm8Vx32JLZOWiyHzgOIPDPJtmxstxjkkwFwUVJk1RB/ VC2zISxHvfpGtKzfII1EkIoCuGzIS0LjT6ZDgvWA= Date: Tue, 19 Dec 2023 12:51:16 -0800 To: mm-commits@vger.kernel.org,willy@infradead.org,shr@devkernel.io,joseph.qi@linux.alibaba.com,jefflexu@linux.alibaba.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-fix-arithmetic-for-bdi-min_ratio.patch added to mm-hotfixes-unstable branch Message-Id: <20231219205117.B6F4EC433C8@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: fix arithmetic for bdi min_ratio has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-fix-arithmetic-for-bdi-min_ratio.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-arithmetic-for-bdi-min_ratio.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Jingbo Xu Subject: mm: fix arithmetic for bdi min_ratio Date: Tue, 19 Dec 2023 22:25:07 +0800 Since now bdi->min_ratio is part per million, fix the wrong arithmetic. Otherwise it will fail with -EINVAL when setting a reasonable min_ratio, as it tries to set min_ratio to (min_ratio * BDI_RATIO_SCALE) in percentage unit, which exceeds 100% anyway. # cat /sys/class/bdi/253\:0/min_ratio 0 # cat /sys/class/bdi/253\:0/max_ratio 100 # echo 1 > /sys/class/bdi/253\:0/min_ratio -bash: echo: write error: Invalid argument Link: https://lkml.kernel.org/r/20231219142508.86265-2-jefflexu@linux.alibaba.com Fixes: 8021fb3232f2 ("mm: split off __bdi_set_min_ratio() function") Signed-off-by: Jingbo Xu Reported-by: Joseph Qi Cc: Matthew Wilcox (Oracle) Cc: Stefan Roesch Signed-off-by: Andrew Morton --- mm/page-writeback.c | 1 - 1 file changed, 1 deletion(-) --- a/mm/page-writeback.c~mm-fix-arithmetic-for-bdi-min_ratio +++ a/mm/page-writeback.c @@ -692,7 +692,6 @@ static int __bdi_set_min_ratio(struct ba if (min_ratio > 100 * BDI_RATIO_SCALE) return -EINVAL; - min_ratio *= BDI_RATIO_SCALE; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { _ Patches currently in -mm which might be from jefflexu@linux.alibaba.com are mm-fix-arithmetic-for-bdi-min_ratio.patch mm-fix-arithmetic-for-max_prop_frac-when-setting-max_ratio.patch