From: Dave Jiang <dave.jiang@xxxxxxxxx> Subject: mm: disallow mappings that conflict for devm_memremap_pages() When pmem namespaces created are smaller than section size, this can cause an 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 a mapping already in the same section and prevent additional mappings from being created if that is the case. Link: http://lkml.kernel.org/r/152909478401.50143.312364396244072931.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Robert Elliott <elliott@xxxxxxx> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/memremap.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) --- a/kernel/memremap.c~mm-disallow-mapping-that-conflict-for-devm_memremap_pages +++ a/kernel/memremap.c @@ -176,10 +176,27 @@ void *devm_memremap_pages(struct device 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 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, _
