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Wed, 5 Aug 2026 15:16:38 +0000 (GMT) Message-ID: <00877570-486d-447b-97c5-6af6f08410e7@linux.ibm.com> Date: Wed, 5 Aug 2026 20:46:36 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 5/5] nvme: raise FDP placement handle cap to U8_MAX and warn on overflow To: Guixin Liu , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Hannes Reinecke , Chaitanya Kulkarni , Kanchan Joshi Cc: linux-nvme@lists.infradead.org References: <20260804021901.3777326-1-kanie@linux.alibaba.com> <20260804021901.3777326-6-kanie@linux.alibaba.com> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20260804021901.3777326-6-kanie@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=E6P9Y6dl c=1 sm=1 tr=0 ts=6a7353db cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=hD80L64hAAAA:8 a=SRrdq9N9AAAA:8 a=VnNF1IyMAAAA:8 a=QwK8Kxzwo6IFX08B6Z8A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: GmH8vi78KXO5dNunWQkYdU7UaUnpDoM9 X-Proofpoint-GUID: I1WJeYI7poI7rev9QvpFyPMfXdx4SlnI X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDEyMCBTYWx0ZWRfX4d63L00Xxclg lWDZnSPpxIucCRiDf0v0ZL0fCQkoltgZoj8kAcezAf2JQQUu7MvIzDE4p3TtgtGRnlZXuajopoU oFgRpmgPQLkNpCT8twlJNFmNCxElgmE= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDEyMCBTYWx0ZWRfX2d12s+d9u1f5 0TVgSxxKh2CcqwQ8M4QPiGlAkwNU0ZitdBmhjp1j4QX46mxDUy1T6cF/Qbif58okfQUDg1+0kBT MGjKF6l93a7VTAwPiLJRLdHm+rvGOnBMdcEEpaGLz9Jh7CusuaBpoTle9y3bb26ZWIVSPHv9Wvd E9cE056iQv5DsWZRMETdu/yk/WkdygB2SU32KTdKsP32sLRj3Em2NYJtKgc0vQZCm4g9JlSl3LU Cy5dChgsNl+jYoz0Iv4cOOVZT2zo0yKdRdA8zSEOV/Z00kBPefTp5aHMxq03dUL11lhhFdILQCu tsqud8JVqHFckYdHnp4qPRN88aAWAcK0e6ECdErsxkbjzVoe5iSNrQvg+GtZfoFVCeHHqp6RoIr 9JR47XD+VH66LzAGz5urZyNaqGMCNBc3p7Sw31DO5QgefkEdQ1zWnrlaUyjiNzOg40pjfcM5XwL sERYE8C8D5JdJc5F/Sg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-05_04,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 suspectscore=0 adultscore=0 spamscore=0 malwarescore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050120 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260805_081657_922816_B9B5E3D6 X-CRM114-Status: GOOD ( 13.23 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 8/4/26 7:49 AM, Guixin Liu wrote: > he RUH status buffer and the placement-handle clamp used S8_MAX - 1 > (126) as the maximum descriptor count. That value was picked only so the > io-mgmt-receive result fit in a page, not because of any protocol or > driver restriction. > > The meaningful upper bound is U8_MAX: write hints (bio->bi_write_stream) > are u8, so placement handles beyond U8_MAX can never be selected. Size > the buffer and clamp nr_plids to U8_MAX, and emit a dev_warn() when the > device reports more handles than the driver tracks so the truncation is > observable. > > Suggested-by: Kanchan Joshi > Signed-off-by: Guixin Liu > Reviewed-by: Kanchan Joshi Looks good to me. Reviewed-by: Nilay Shroff