From: John Groves Two fixes for virtual address handling in fsdev: 1. 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. 2. Convert the WARN_ON to a fatal error when pgmap_phys > phys. This condition means the remapped region starts after the device's data region, which is an impossible state. Previously the probe continued with data_offset=0, leaving virt_addr silently misaligned. Now probe returns -EINVAL with a diagnostic message. Fixes: 759455848df0b ("dax: Save the kva from memremap") Signed-off-by: John Groves --- drivers/dax/fsdev.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c index 42aac7e952516..aac0130ab2833 100644 --- a/drivers/dax/fsdev.c +++ b/drivers/dax/fsdev.c @@ -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 @@ -313,8 +310,13 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax) u64 phys = dev_dax->ranges[0].range.start; u64 pgmap_phys = dev_dax->pgmap[0].range.start; - if (!WARN_ON(pgmap_phys > phys)) - data_offset = phys - pgmap_phys; + if (pgmap_phys > phys) { + dev_err(dev, "pgmap start %#llx exceeds data start %#llx\n", + pgmap_phys, phys); + rc = -EINVAL; + goto err_pgmap; + } + data_offset = phys - pgmap_phys; pr_debug("%s: offset detected phys=%llx pgmap_phys=%llx offset=%llx\n", __func__, phys, pgmap_phys, data_offset); -- 2.53.0