| Message ID | 152909478401.50143.312364396244072931.stgit@djiang5-desk3.ch.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Andrew, is it possible to pick up this patch? Thanks! On 06/15/2018 01:33 PM, Dave Jiang wrote: > When pmem namespaces created are smaller than section size, this can cause > issue during removal and gpf was observed: > > [ 249.613597] general protection fault: 0000 1 SMP PTI > [ 249.725203] CPU: 36 PID: 3941 Comm: ndctl Tainted: G W > 4.14.28-1.el7uek.x86_64 #2 > [ 249.745495] task: ffff88acda150000 task.stack: ffffc900233a4000 > [ 249.752107] RIP: 0010:__put_page+0x56/0x79 > [ 249.844675] Call Trace: > [ 249.847410] devm_memremap_pages_release+0x155/0x23a > [ 249.852953] release_nodes+0x21e/0x260 > [ 249.857138] devres_release_all+0x3c/0x48 > [ 249.861606] device_release_driver_internal+0x15c/0x207 > [ 249.867439] device_release_driver+0x12/0x14 > [ 249.872204] unbind_store+0xba/0xd8 > [ 249.876098] drv_attr_store+0x27/0x31 > [ 249.880186] sysfs_kf_write+0x3f/0x46 > [ 249.884266] kernfs_fop_write+0x10f/0x18b > [ 249.888734] __vfs_write+0x3a/0x16d > [ 249.892628] ? selinux_file_permission+0xe5/0x116 > [ 249.897881] ? security_file_permission+0x41/0xbb > [ 249.903133] vfs_write+0xb2/0x1a1 > [ 249.906835] ? syscall_trace_enter+0x1ce/0x2b8 > [ 249.911795] SyS_write+0x55/0xb9 > [ 249.915397] do_syscall_64+0x79/0x1ae > [ 249.919485] entry_SYSCALL_64_after_hwframe+0x3d/0x0 > > Add code to check whether we have mapping already in the same section and > prevent additional mapping from created if that is the case. > > Signed-off-by: Dave Jiang <dave.jiang@intel.com> > --- > > v2: Change dev_warn() to dev_WARN() to provide helpful backtrace. (Robert E) > > kernel/memremap.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/kernel/memremap.c b/kernel/memremap.c > index 5857267a4af5..a734b1747466 100644 > --- a/kernel/memremap.c > +++ b/kernel/memremap.c > @@ -176,10 +176,27 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > unsigned long pfn, pgoff, order; > pgprot_t pgprot = PAGE_KERNEL; > int error, nid, is_ram; > + struct dev_pagemap *conflict_pgmap; > > align_start = res->start & ~(SECTION_SIZE - 1); > align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) > - align_start; > + align_end = align_start + align_size - 1; > + > + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); > + if (conflict_pgmap) { > + dev_WARN(dev, "Conflicting mapping in same section\n"); > + put_dev_pagemap(conflict_pgmap); > + return ERR_PTR(-ENOMEM); > + } > + > + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); > + if (conflict_pgmap) { > + dev_WARN(dev, "Conflicting mapping in same section\n"); > + put_dev_pagemap(conflict_pgmap); > + return ERR_PTR(-ENOMEM); > + } > + > is_ram = region_intersects(align_start, align_size, > IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); > > @@ -199,7 +216,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > > mutex_lock(&pgmap_lock); > error = 0; > - align_end = align_start + align_size - 1; > > foreach_order_pgoff(res, order, pgoff) { > error = __radix_tree_insert(&pgmap_radix, >
On Fri, 15 Jun 2018 13:33:39 -0700 Dave Jiang <dave.jiang@intel.com> wrote: > When pmem namespaces created are smaller than section size, this can cause > issue during removal and gpf was observed: > > ... > > Add code to check whether we have mapping already in the same section and > prevent additional mapping from created if that is the case. > Which kernel version(s) do you believe need this fix, and why?
On 07/17/2018 02:37 PM, Andrew Morton wrote: > On Fri, 15 Jun 2018 13:33:39 -0700 Dave Jiang <dave.jiang@intel.com> wrote: > >> When pmem namespaces created are smaller than section size, this can cause >> issue during removal and gpf was observed: >> >> ... >> >> Add code to check whether we have mapping already in the same section and >> prevent additional mapping from created if that is the case. >> > > Which kernel version(s) do you believe need this fix, and why? > It really should go into 4.18-rc and backported to stable since without it a GPF can be triggered when pmem namespaces smaller than section size are constructed.
Hi, Dave, Dave Jiang <dave.jiang@intel.com> writes: > When pmem namespaces created are smaller than section size, this can cause > issue during removal and gpf was observed: > > [ 249.613597] general protection fault: 0000 1 SMP PTI > [ 249.725203] CPU: 36 PID: 3941 Comm: ndctl Tainted: G W > 4.14.28-1.el7uek.x86_64 #2 > [ 249.745495] task: ffff88acda150000 task.stack: ffffc900233a4000 > [ 249.752107] RIP: 0010:__put_page+0x56/0x79 > [ 249.844675] Call Trace: > [ 249.847410] devm_memremap_pages_release+0x155/0x23a > [ 249.852953] release_nodes+0x21e/0x260 > [ 249.857138] devres_release_all+0x3c/0x48 > [ 249.861606] device_release_driver_internal+0x15c/0x207 > [ 249.867439] device_release_driver+0x12/0x14 > [ 249.872204] unbind_store+0xba/0xd8 > [ 249.876098] drv_attr_store+0x27/0x31 > [ 249.880186] sysfs_kf_write+0x3f/0x46 > [ 249.884266] kernfs_fop_write+0x10f/0x18b > [ 249.888734] __vfs_write+0x3a/0x16d > [ 249.892628] ? selinux_file_permission+0xe5/0x116 > [ 249.897881] ? security_file_permission+0x41/0xbb > [ 249.903133] vfs_write+0xb2/0x1a1 > [ 249.906835] ? syscall_trace_enter+0x1ce/0x2b8 > [ 249.911795] SyS_write+0x55/0xb9 > [ 249.915397] do_syscall_64+0x79/0x1ae > [ 249.919485] entry_SYSCALL_64_after_hwframe+0x3d/0x0 > > Add code to check whether we have mapping already in the same section and > prevent additional mapping from created if that is the case. > > Signed-off-by: Dave Jiang <dave.jiang@intel.com> > --- > > v2: Change dev_warn() to dev_WARN() to provide helpful backtrace. (Robert E) OK, I can reproduce the issue. What I don't like about your patch is that you can still get yourself into trouble. Just create a namespace with a size that isn't aligned to 128MB, and then all further create-namespace operations will fail. The only "fix" is to delete the odd-sized namespace and try again. And that warning message doesn't really help the administrator to figure this out. Why can't we simply round up to the next section automatically? Either that, or have the kernel export a minimum namespace size of 128MB, and have ndctl enforce it? I know we had some requests for 4MB namespaces, but it doesn't sound like those will be very useful if they're going to waste 124MB of space. Or, we could try to fix this problem of having multiple namespace co-exist in the same memblock section. That seems like the most obvious fix, but there must be a reason you didn't pursue it. Dave, what do you think is the most viable option? Cheers, Jeff > kernel/memremap.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/kernel/memremap.c b/kernel/memremap.c > index 5857267a4af5..a734b1747466 100644 > --- a/kernel/memremap.c > +++ b/kernel/memremap.c > @@ -176,10 +176,27 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > unsigned long pfn, pgoff, order; > pgprot_t pgprot = PAGE_KERNEL; > int error, nid, is_ram; > + struct dev_pagemap *conflict_pgmap; > > align_start = res->start & ~(SECTION_SIZE - 1); > align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) > - align_start; > + align_end = align_start + align_size - 1; > + > + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); > + if (conflict_pgmap) { > + dev_WARN(dev, "Conflicting mapping in same section\n"); > + put_dev_pagemap(conflict_pgmap); > + return ERR_PTR(-ENOMEM); > + } > + > + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); > + if (conflict_pgmap) { > + dev_WARN(dev, "Conflicting mapping in same section\n"); > + put_dev_pagemap(conflict_pgmap); > + return ERR_PTR(-ENOMEM); > + } > + > is_ram = region_intersects(align_start, align_size, > IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); > > @@ -199,7 +216,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > > mutex_lock(&pgmap_lock); > error = 0; > - align_end = align_start + align_size - 1; > > foreach_order_pgoff(res, order, pgoff) { > error = __radix_tree_insert(&pgmap_radix, > > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm
On Wed, Jul 18, 2018 at 02:27:31PM -0400, Jeff Moyer wrote: > Hi, Dave, > > Dave Jiang <dave.jiang@intel.com> writes: > > > When pmem namespaces created are smaller than section size, this can cause > > issue during removal and gpf was observed: > > > > Add code to check whether we have mapping already in the same section and > > prevent additional mapping from created if that is the case. > > > > Signed-off-by: Dave Jiang <dave.jiang@intel.com> > > --- > > > > v2: Change dev_warn() to dev_WARN() to provide helpful backtrace. (Robert E) > > OK, I can reproduce the issue. What I don't like about your patch is > that you can still get yourself into trouble. Just create a namespace > with a size that isn't aligned to 128MB, and then all further > create-namespace operations will fail. The only "fix" is to delete the > odd-sized namespace and try again. And that warning message doesn't > really help the administrator to figure this out. > > Why can't we simply round up to the next section automatically? Either > that, or have the kernel export a minimum namespace size of 128MB, and > have ndctl enforce it? I know we had some requests for 4MB namespaces, > but it doesn't sound like those will be very useful if they're going to > waste 124MB of space. > > Or, we could try to fix this problem of having multiple namespace > co-exist in the same memblock section. That seems like the most obvious > fix, but there must be a reason you didn't pursue it. > > Dave, what do you think is the most viable option? Just as a reminder, the desire for small pmem devices comes from cloud usecases where you have teeny tiny layers, each of which might contain a single package (eg a webserver or a database). Because you're going to run tens of thousands of instances, you don't want each machine to keep a copy of the program text in pagecache; you want to have it in-memory once and then DAX-map it in each guest. While it's OK to waste a certain amount of each guest's physical memory, when you have hundreds or thousands of these tiny layers, it adds up.
On 07/18/2018 11:27 AM, Jeff Moyer wrote: > Hi, Dave, > > Dave Jiang <dave.jiang@intel.com> writes: > >> When pmem namespaces created are smaller than section size, this can cause >> issue during removal and gpf was observed: >> >> [ 249.613597] general protection fault: 0000 1 SMP PTI >> [ 249.725203] CPU: 36 PID: 3941 Comm: ndctl Tainted: G W >> 4.14.28-1.el7uek.x86_64 #2 >> [ 249.745495] task: ffff88acda150000 task.stack: ffffc900233a4000 >> [ 249.752107] RIP: 0010:__put_page+0x56/0x79 >> [ 249.844675] Call Trace: >> [ 249.847410] devm_memremap_pages_release+0x155/0x23a >> [ 249.852953] release_nodes+0x21e/0x260 >> [ 249.857138] devres_release_all+0x3c/0x48 >> [ 249.861606] device_release_driver_internal+0x15c/0x207 >> [ 249.867439] device_release_driver+0x12/0x14 >> [ 249.872204] unbind_store+0xba/0xd8 >> [ 249.876098] drv_attr_store+0x27/0x31 >> [ 249.880186] sysfs_kf_write+0x3f/0x46 >> [ 249.884266] kernfs_fop_write+0x10f/0x18b >> [ 249.888734] __vfs_write+0x3a/0x16d >> [ 249.892628] ? selinux_file_permission+0xe5/0x116 >> [ 249.897881] ? security_file_permission+0x41/0xbb >> [ 249.903133] vfs_write+0xb2/0x1a1 >> [ 249.906835] ? syscall_trace_enter+0x1ce/0x2b8 >> [ 249.911795] SyS_write+0x55/0xb9 >> [ 249.915397] do_syscall_64+0x79/0x1ae >> [ 249.919485] entry_SYSCALL_64_after_hwframe+0x3d/0x0 >> >> Add code to check whether we have mapping already in the same section and >> prevent additional mapping from created if that is the case. >> >> Signed-off-by: Dave Jiang <dave.jiang@intel.com> >> --- >> >> v2: Change dev_warn() to dev_WARN() to provide helpful backtrace. (Robert E) > > OK, I can reproduce the issue. What I don't like about your patch is > that you can still get yourself into trouble. Just create a namespace > with a size that isn't aligned to 128MB, and then all further > create-namespace operations will fail. The only "fix" is to delete the > odd-sized namespace and try again. And that warning message doesn't > really help the administrator to figure this out. > > Why can't we simply round up to the next section automatically? Either > that, or have the kernel export a minimum namespace size of 128MB, and > have ndctl enforce it? I know we had some requests for 4MB namespaces, > but it doesn't sound like those will be very useful if they're going to > waste 124MB of space. > > Or, we could try to fix this problem of having multiple namespace > co-exist in the same memblock section. That seems like the most obvious > fix, but there must be a reason you didn't pursue it. > > Dave, what do you think is the most viable option? I know Dan has plans to fix the problem and he has some patches I believe. But I didn't get a chance to talk to him about this before he left for his sabbatical. This patch is meant to bandaid the kernel oops until we can fix the issue properly. But that will need to wait until Dan is back. > > Cheers, > Jeff > > >> kernel/memremap.c | 18 +++++++++++++++++- >> 1 file changed, 17 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/memremap.c b/kernel/memremap.c >> index 5857267a4af5..a734b1747466 100644 >> --- a/kernel/memremap.c >> +++ b/kernel/memremap.c >> @@ -176,10 +176,27 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) >> unsigned long pfn, pgoff, order; >> pgprot_t pgprot = PAGE_KERNEL; >> int error, nid, is_ram; >> + struct dev_pagemap *conflict_pgmap; >> >> align_start = res->start & ~(SECTION_SIZE - 1); >> align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) >> - align_start; >> + align_end = align_start + align_size - 1; >> + >> + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); >> + if (conflict_pgmap) { >> + dev_WARN(dev, "Conflicting mapping in same section\n"); >> + put_dev_pagemap(conflict_pgmap); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); >> + if (conflict_pgmap) { >> + dev_WARN(dev, "Conflicting mapping in same section\n"); >> + put_dev_pagemap(conflict_pgmap); >> + return ERR_PTR(-ENOMEM); >> + } >> + >> is_ram = region_intersects(align_start, align_size, >> IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); >> >> @@ -199,7 +216,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) >> >> mutex_lock(&pgmap_lock); >> error = 0; >> - align_end = align_start + align_size - 1; >> >> foreach_order_pgoff(res, order, pgoff) { >> error = __radix_tree_insert(&pgmap_radix, >> >> _______________________________________________ >> Linux-nvdimm mailing list >> Linux-nvdimm@lists.01.org >> https://lists.01.org/mailman/listinfo/linux-nvdimm
diff --git a/kernel/memremap.c b/kernel/memremap.c index 5857267a4af5..a734b1747466 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -176,10 +176,27 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) unsigned long pfn, pgoff, order; pgprot_t pgprot = PAGE_KERNEL; int error, nid, is_ram; + struct dev_pagemap *conflict_pgmap; align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; + align_end = align_start + align_size - 1; + + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); + if (conflict_pgmap) { + dev_WARN(dev, "Conflicting mapping in same section\n"); + put_dev_pagemap(conflict_pgmap); + return ERR_PTR(-ENOMEM); + } + + conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); + if (conflict_pgmap) { + dev_WARN(dev, "Conflicting mapping in same section\n"); + put_dev_pagemap(conflict_pgmap); + return ERR_PTR(-ENOMEM); + } + is_ram = region_intersects(align_start, align_size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); @@ -199,7 +216,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) mutex_lock(&pgmap_lock); error = 0; - align_end = align_start + align_size - 1; foreach_order_pgoff(res, order, pgoff) { error = __radix_tree_insert(&pgmap_radix,
When pmem namespaces created are smaller than section size, this can cause issue during removal and gpf was observed: [ 249.613597] general protection fault: 0000 1 SMP PTI [ 249.725203] CPU: 36 PID: 3941 Comm: ndctl Tainted: G W 4.14.28-1.el7uek.x86_64 #2 [ 249.745495] task: ffff88acda150000 task.stack: ffffc900233a4000 [ 249.752107] RIP: 0010:__put_page+0x56/0x79 [ 249.844675] Call Trace: [ 249.847410] devm_memremap_pages_release+0x155/0x23a [ 249.852953] release_nodes+0x21e/0x260 [ 249.857138] devres_release_all+0x3c/0x48 [ 249.861606] device_release_driver_internal+0x15c/0x207 [ 249.867439] device_release_driver+0x12/0x14 [ 249.872204] unbind_store+0xba/0xd8 [ 249.876098] drv_attr_store+0x27/0x31 [ 249.880186] sysfs_kf_write+0x3f/0x46 [ 249.884266] kernfs_fop_write+0x10f/0x18b [ 249.888734] __vfs_write+0x3a/0x16d [ 249.892628] ? selinux_file_permission+0xe5/0x116 [ 249.897881] ? security_file_permission+0x41/0xbb [ 249.903133] vfs_write+0xb2/0x1a1 [ 249.906835] ? syscall_trace_enter+0x1ce/0x2b8 [ 249.911795] SyS_write+0x55/0xb9 [ 249.915397] do_syscall_64+0x79/0x1ae [ 249.919485] entry_SYSCALL_64_after_hwframe+0x3d/0x0 Add code to check whether we have mapping already in the same section and prevent additional mapping from created if that is the case. Signed-off-by: Dave Jiang <dave.jiang@intel.com> --- v2: Change dev_warn() to dev_WARN() to provide helpful backtrace. (Robert E) kernel/memremap.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)