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Tue, 7 Feb 2023 07:47:16 GMT Received: from [10.239.132.245] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.36; Mon, 6 Feb 2023 23:47:14 -0800 Message-ID: Date: Tue, 7 Feb 2023 15:46:53 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH] mm: kfence: export kfence_enabled as global variables To: Marco Elver CC: , , , , , , Mark Rutland References: <1675750519-1064-1-git-send-email-quic_zhenhuah@quicinc.com> Content-Language: en-US From: Zhenhua Huang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: o3d2D_2aJR2bnWI81joV-PU2NrwfB2iY X-Proofpoint-ORIG-GUID: o3d2D_2aJR2bnWI81joV-PU2NrwfB2iY X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-02-07_01,2023-02-06_03,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 priorityscore=1501 mlxlogscore=999 bulkscore=0 clxscore=1011 malwarescore=0 spamscore=0 adultscore=0 lowpriorityscore=0 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302070070 X-Rspamd-Queue-Id: 8FB2C1C0003 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: zoo3yb6z74o7i1nub1ejad66xg4xmfhm X-HE-Tag: 1675756044-238325 X-HE-Meta: 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 WwAJC1E/ zKetR4bfucyQqmRlwv+i747ZAt6kDGF/2jpRw0ftWwPFttTAJUANGrlY6kXi45ah44iWK48DeQ/aQZ/cGJITy7pbSSlZxixCdgoKBXXnQW0jIeS4+ZCboz17ICki8I77gIjW9WNDMYYEz5zzeF4H43Al41vvv2cDcz8TgaO/AeHEZXbLAWSR585KDeDr/J3MUruLrMu3CQv1d2hxrNLK9B8uWKf/C+aduRjmwfRPyzhiQU4gpINoQRueDEoX4boj3PZioSzOkZB1Tzko4D+kypRmCLsy8qo6vGf/VhJdZdx91ZeEddt4bbBMfFJeXBagJVe+aqvfIdNf/tRrb1pnzayXwaSmiRyFlixnXqb4ZHA1wgUc= 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: Thanks Marco! On 2023/2/7 15:19, Marco Elver wrote: > On Tue, 7 Feb 2023 at 07:15, Zhenhua Huang wrote: >> >> Export the variable to ease the judgement of whether kfence enabled >> at runtime. It should be more precise than through kernel config >> "CONFIG_KFENCE". >> >> For example We can disable kfence at runtime using bootargs >> "kfence.sample_interval=0" but CONFIG_KFENCE enabled. >> It was false positive. >> >> Signed-off-by: Zhenhua Huang >> --- >> arch/arm64/mm/pageattr.c | 3 ++- >> include/linux/kfence.h | 2 ++ >> mm/kfence/core.c | 2 +- >> 3 files changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c >> index 79dd201..208d780 100644 >> --- a/arch/arm64/mm/pageattr.c >> +++ b/arch/arm64/mm/pageattr.c >> @@ -7,6 +7,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -27,7 +28,7 @@ bool can_set_direct_map(void) >> * protect/unprotect single pages. >> */ >> return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() || >> - IS_ENABLED(CONFIG_KFENCE); >> + kfence_enabled; > > Unfortunately this won't work, because it's possible to enable KFENCE > after the kernel has booted with e.g.: echo 100 > > /sys/module/kfence/parameters/sample_interval Yeah, got it. Thanks for catching it. > > What is the problem you have encountered? Is the page-granular direct > map causing issues? We're working on a low memory target, page-granular mapping costed more (2M per 1GB) memory. Due to GKI constraints, it is not easy to disable CONFIG_KFENCE. So my intention was to move the judgement to runtime configurable w/ CONFIG_KFENCE on... Do you have any further suggestion/proposal on this? Many Thanks! Thanks, Zhenhua