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@xxxxxxxxx>
---
kernel/memremap.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 5857267a4af5..d9ac547993cb 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,
