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dax/fsdev: use __va(phys) for kaddr in direct_access

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Use __va(phys) instead of virt_addr + linear_offset for the kaddr
return in __fsdev_dax_direct_access(). The previous code added a
device-linear byte offset to virt_addr (which is __va of ranges[0]),
but for multi-range devices with physical gaps between ranges, this
linear arithmetic crosses the gap and produces a wrong kernel virtual
address. Using __va(phys) where phys comes from dax_pgoff_to_phys()
is correct for any range layout because the direct map translates
each physical address independently.

This leaves dev_dax->virt_addr write-only, so remove the field
(suggested by Dave Jiang).

Fixes: 759455848d ("dax: Save the kva from memremap")

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: John Groves <john@groves.net>
Link: https://patch.msgid.link/0100019ecc096de8-8bc254a7-d2cc-44b6-82b1-1394fda8bb41-000000@email.amazonses.com
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
This commit is contained in:
John Groves 2026-06-15 16:07:10 +00:00 committed by Alison Schofield
parent f48884ac31
commit ff7c73fca7
2 changed files with 2 additions and 8 deletions
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2
drivers/dax/dax-private.h
View File

@ -69,7 +69,6 @@ struct dev_dax_range {
* data while the device is activated in the driver.
* @region: parent region
* @dax_dev: core dax functionality
* @virt_addr: kva from memremap; used by fsdev_dax
* @cached_size: size of daxdev cached by fsdev_dax
* @align: alignment of this instance
* @target_node: effective numa node if dev_dax memory range is onlined
@ -85,7 +84,6 @@ struct dev_dax_range {
struct dev_dax {
struct dax_region *region;
struct dax_device *dax_dev;
void *virt_addr;
u64 cached_size;
unsigned int align;
int target_node;

8
drivers/dax/fsdev.c
View File

@ -51,9 +51,7 @@ static long __fsdev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
struct dev_dax *dev_dax = dax_get_private(dax_dev);
size_t size = nr_pages << PAGE_SHIFT;
size_t offset = pgoff << PAGE_SHIFT;
void *virt_addr = dev_dax->virt_addr + offset;
phys_addr_t phys;
unsigned long local_pfn;
phys = dax_pgoff_to_phys(dev_dax, pgoff, size);
if (phys == -1) {
@ -63,11 +61,10 @@ static long __fsdev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
}
if (kaddr)
*kaddr = virt_addr;
*kaddr = __va(phys);
local_pfn = PHYS_PFN(phys);
if (pfn)
*pfn = local_pfn;
*pfn = PHYS_PFN(phys);
/*
* Use cached_size which was computed at probe time. The size cannot
@ -351,7 +348,6 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
pr_debug("%s: offset detected phys=%llx pgmap_phys=%llx offset=%llx\n",
__func__, phys, pgmap_phys, data_offset);
}
dev_dax->virt_addr = addr + data_offset;
inode = dax_inode(dax_dev);
cdev = inode->i_cdev;