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authorDave Jiang <dave.jiang@intel.com>2017-03-10 21:24:27 +0100
committerDan Williams <dan.j.williams@intel.com>2017-03-11 04:55:53 +0100
commit70b085b06c4560a69e95607f77bb4c2b2e41943c (patch)
treee667d70ececd084f7a365600c596e2d81ec4bcaf /drivers/dax
parentdevice-dax: fix pmd/pte fault fallback handling (diff)
downloadlinux-70b085b06c4560a69e95607f77bb4c2b2e41943c.tar.xz
linux-70b085b06c4560a69e95607f77bb4c2b2e41943c.zip
device-dax: fix pud fault fallback handling
Jeff Moyer reports: With a device dax alignment of 4KB or 2MB, I get sigbus when running the attached fio job file for the current kernel (4.11.0-rc1+). If I specify an alignment of 1GB, it works. I turned on debug output, and saw that it was failing in the huge fault code. dax dax1.0: dax_open dax dax1.0: dax_mmap dax dax1.0: dax_dev_huge_fault: fio: write (0x7f08f0a00000 - dax dax1.0: __dax_dev_pud_fault: phys_to_pgoff(0xffffffffcf60) dax dax1.0: dax_release fio config for reproduce: [global] ioengine=dev-dax direct=0 filename=/dev/dax0.0 bs=2m [write] rw=write [read] stonewall rw=read The driver fails to fallback when taking a fault that is larger than the device alignment, or handling a larger fault when a smaller mapping is already established. While we could support larger mappings for a device with a smaller alignment, that change is too large for the immediate fix. The simplest change is to force fallback until the fault size matches the alignment. Reported-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dax')
-rw-r--r--drivers/dax/dax.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index a284dc532e46..523fecec7bda 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -518,6 +518,8 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
phys_addr_t phys;
pgoff_t pgoff;
pfn_t pfn;
+ unsigned int fault_size = PUD_SIZE;
+
if (check_vma(dax_dev, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
@@ -534,6 +536,16 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
}
+ if (fault_size < dax_region->align)
+ return VM_FAULT_SIGBUS;
+ else if (fault_size > dax_region->align)
+ return VM_FAULT_FALLBACK;
+
+ /* if we are outside of the VMA */
+ if (pud_addr < vmf->vma->vm_start ||
+ (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
+ return VM_FAULT_SIGBUS;
+
pgoff = linear_page_index(vmf->vma, pud_addr);
phys = pgoff_to_phys(dax_dev, pgoff, PUD_SIZE);
if (phys == -1) {