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Tue, 27 Oct 2026 03:09:09 -0700 (PDT) Received: from unicorn.lan.internal ([2a0d:3341:b894:4600:8f9a:af38:72d6:7c0e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a35a5822a7sm266582155e9.11.2026.10.27.03.09.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 03:09:08 -0700 (PDT) From: Giuseppe Piscitelli To: "James E.J. Bottomley" , "Martin K. Petersen" Cc: Bart Van Assche , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] scsi: core: Balance the pseudo target reap reference Date: Tue, 27 Oct 2026 11:08:50 +0100 Message-ID: <20261027100859.1031135-1-ooonea@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261026202119.667348-1-ooonea@gmail.com> References: X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit With memory allocation profiling enabled, unloading scsi_debug reports allocations left at module unload. A stock Linux 7.2.11 VM without OpenZFS emitted the following on each of three load/unload cycles: [ 1.644665] drivers/scsi/scsi_debug.c:8863 module scsi_debug func:sdebug_add_host_helper has 1024 allocated at module unload [ 1.656260] drivers/scsi/scsi_debug.c:1261 module scsi_debug func:sdebug_target_alloc has 16 allocated at module unload scsi_alloc_target() supplies a reap reference for its caller. The SCSI device initializer takes another reference, which device removal drops. scsi_get_pseudo_sdev() drops its caller reference only when device allocation fails. On success the target cannot be destroyed, retaining its driver-private data and its parent host and adapter. Drop the caller reference in the common cleanup path, as the other scsi_alloc_target() callers do. Fixes: d630fbf6fc8c ("scsi: core: Support allocating a pseudo SCSI device") Signed-off-by: Giuseppe Piscitelli --- OpenAI Codex analyzed the teardown diagnostics and wrote this fix and its local validation. The new unpatched capture reproduces the symptom; it does not establish which of this fix and the separately proposed scsi_debug asynchronous cleanup fix removes each diagnostic. Changes in v2: - Include the allocation-at-unload diagnostics requested by Bart. - No code changes. Earlier validation covered four constructor/reference-count cases, a Linux 7.3 build and three ordinary corrected-module lifecycles. The new stock 7.2.11 run above captures the unpatched diagnostics only; no new patched-kernel build or comparison was run. drivers/scsi/scsi_scan.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 0f0f243..90e67f3 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -2156,14 +2156,13 @@ struct scsi_device *scsi_get_pseudo_sdev(struct Scsi_Host *shost) goto out; sdev = scsi_alloc_sdev(starget, U64_MAX, NULL); - if (!sdev) { - scsi_target_reap(starget); + if (!sdev) goto put_target; - } sdev->borken = 0; put_target: + scsi_target_reap(starget); /* See also the get_device(dev) call in scsi_alloc_target(). */ put_device(&starget->dev); base-commit: 6a53f401e671b75c129245e371ca6e9d47fc3c9a -- 2.54.0