From 867dfe342118b1ea0256a85f7c0d9ceb0ead032a Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 25 Oct 2016 17:52:04 +0200 Subject: nvdimm: make CONFIG_NVDIMM_DAX 'bool' A bugfix just tried to address a randconfig build problem and introduced a variant of the same problem: with CONFIG_LIBNVDIMM=y and CONFIG_NVDIMM_DAX=m, the nvdimm module now fails to link: drivers/nvdimm/built-in.o: In function `to_nd_device_type': bus.c:(.text+0x1b5d): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nd_region_notify_driver_action.constprop.2': region_devs.c:(.text+0x6b6c): undefined reference to `is_nd_dax' region_devs.c:(.text+0x6b8c): undefined reference to `to_nd_dax' drivers/nvdimm/built-in.o: In function `nd_region_probe': region.c:(.text+0x70f3): undefined reference to `nd_dax_create' drivers/nvdimm/built-in.o: In function `mode_show': namespace_devs.c:(.text+0xa196): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nvdimm_namespace_common_probe': (.text+0xa55f): undefined reference to `is_nd_dax' drivers/nvdimm/built-in.o: In function `nvdimm_namespace_common_probe': (.text+0xa56e): undefined reference to `to_nd_dax' This reverts the earlier fix, making NVDIMM_DAX a 'bool' option again as it should be (it gets linked into the libnvdimm module). To fix the original problem, I'm adding a dependency on LIBNVDIMM to DEV_DAX_PMEM, which ensures we can't have that one built-in if the rest is a module. Fixes: 4e65e9381c7a ("/dev/dax: fix Kconfig dependency build breakage") Signed-off-by: Arnd Bergmann Reviewed-by: Ross Zwisler Signed-off-by: Dan Williams --- drivers/dax/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/dax') diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index daadd20aa936..3e2ab3b14eea 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -14,7 +14,7 @@ if DEV_DAX config DEV_DAX_PMEM tristate "PMEM DAX: direct access to persistent memory" - depends on NVDIMM_DAX + depends on LIBNVDIMM && NVDIMM_DAX default DEV_DAX help Support raw access to persistent memory. Note that this -- cgit v1.2.3 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') 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') 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 From 4cb19355ea19995941ccaad115dbfac6b75215ca Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 16 Nov 2016 09:00:38 -0800 Subject: device-dax: fail all private mapping attempts The device-dax implementation originally tried to be tricky and allow private read-only mappings, but in the process allowed writable MAP_PRIVATE + MAP_NORESERVE mappings. For simplicity and predictability just fail all private mapping attempts since device-dax memory is statically allocated and will never support overcommit. Cc: Cc: Dave Hansen Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Reported-by: Pawel Lebioda Signed-off-by: Dan Williams --- drivers/dax/dax.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c index 0e499bfca41c..3d94ff20fdca 100644 --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -270,8 +270,8 @@ static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma, if (!dax_dev->alive) return -ENXIO; - /* prevent private / writable mappings from being established */ - if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) { + /* prevent private mappings from being established */ + if ((vma->vm_flags & VM_SHARED) != VM_SHARED) { dev_info(dev, "%s: %s: fail, attempted private mapping\n", current->comm, func); return -EINVAL; -- cgit v1.2.3 From 325896ffdf90f7cbd59fb873b7ba20d60d1ddf3c Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 6 Dec 2016 17:03:35 -0800 Subject: device-dax: fix private mapping restriction, permit read-only Hugh notes in response to commit 4cb19355ea19 "device-dax: fail all private mapping attempts": "I think that is more restrictive than you intended: haven't tried, but I believe it rejects a PROT_READ, MAP_SHARED, O_RDONLY fd mmap, leaving no way to mmap /dev/dax without write permission to it." Indeed it does restrict read-only mappings, switch to checking VM_MAYSHARE, not VM_SHARED. Cc: Cc: Dave Hansen Cc: Pawel Lebioda Fixes: 4cb19355ea19 ("device-dax: fail all private mapping attempts") Reported-by: Hugh Dickins Signed-off-by: Dan Williams --- drivers/dax/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/dax') diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c index 3d94ff20fdca..286447a83dab 100644 --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -271,7 +271,7 @@ static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma, return -ENXIO; /* prevent private mappings from being established */ - if ((vma->vm_flags & VM_SHARED) != VM_SHARED) { + if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { dev_info(dev, "%s: %s: fail, attempted private mapping\n", current->comm, func); return -EINVAL; -- cgit v1.2.3