From 52e73eb2872c9af6f382b2b22954ca8214397a4e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 27 Oct 2016 17:04:05 -0700 Subject: device-dax: fix percpu_ref_exit ordering We need to wait until the percpu_ref is released before exit. Otherwise, we sometimes lose the race and trigger this new warning that was added in v4.9 (commit a67823c1ed10 "percpu-refcount: init ->confirm_switch member properly"): WARNING: CPU: 0 PID: 3629 at lib/percpu-refcount.c:107 percpu_ref_exit+0x51/0x60 [..] Call Trace: [] dump_stack+0x85/0xc2 [] __warn+0xcb/0xf0 [] warn_slowpath_null+0x1d/0x20 [] percpu_ref_exit+0x51/0x60 [] dax_pmem_percpu_exit+0x1a/0x50 [dax_pmem] [] devm_action_release+0xf/0x20 Cc: Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Signed-off-by: Dan Williams --- drivers/dax/pmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/dax/pmem.c') diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index 9630d8837ba9..4a15fa5df98b 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -44,7 +44,6 @@ static void dax_pmem_percpu_exit(void *data) dev_dbg(dax_pmem->dev, "%s\n", __func__); percpu_ref_exit(ref); - wait_for_completion(&dax_pmem->cmp); } static void dax_pmem_percpu_kill(void *data) @@ -54,6 +53,7 @@ static void dax_pmem_percpu_kill(void *data) dev_dbg(dax_pmem->dev, "%s\n", __func__); percpu_ref_kill(ref); + wait_for_completion(&dax_pmem->cmp); } static int dax_pmem_probe(struct device *dev) -- cgit v1.2.3 From 6a84fb4b4e439a8ef0ce19ec7e7661ad76f655c9 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 28 Oct 2016 14:34:51 -0700 Subject: device-dax: check devm_nsio_enable() return value If the dax_pmem driver is passed a resource that is already busy the driver probe attempt should fail with a message like the following: dax_pmem dax0.1: could not reserve region [mem 0x100000000-0x11fffffff] However, if we do not catch the error we crash for the obvious reason of accessing memory that is not mapped. BUG: unable to handle kernel paging request at ffffc90020001000 IP: [] __memcpy+0x12/0x20 [..] Call Trace: [] ? nsio_rw_bytes+0x60/0x180 [] nd_pfn_validate+0x75/0x320 [] nvdimm_setup_pfn+0xb9/0x5d0 [] ? devm_nsio_enable+0xff/0x110 [] dax_pmem_probe+0x59/0x260 Cc: Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory") Reported-by: Dave Hansen Signed-off-by: Dan Williams --- drivers/dax/pmem.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/dax/pmem.c') diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index 4a15fa5df98b..73c6ce93a0d9 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -78,7 +78,9 @@ static int dax_pmem_probe(struct device *dev) nsio = to_nd_namespace_io(&ndns->dev); /* parse the 'pfn' info block via ->rw_bytes */ - devm_nsio_enable(dev, nsio); + rc = devm_nsio_enable(dev, nsio); + if (rc) + return rc; altmap = nvdimm_setup_pfn(nd_pfn, &res, &__altmap); if (IS_ERR(altmap)) return PTR_ERR(altmap); -- cgit v1.2.3