On Tue, Jan 26, 2016 at 11:46 AM, Julian Margetson <runaway@xxxxxxxx> wrote:
> On 1/26/2016 2:37 PM, Dan Williams wrote:
>
> pfn_t_to_page() honors the flags in the pfn_t value to determine if a
> pfn is backed by a page. However, vm_insert_mixed() was originally
> written to use pfn_valid() to make this determination. To restore the
> old/correct behavior, ignore the pfn_t flags in the !pfn_t_devmap() case
> and fallback to trusting pfn_valid().
>
> Fixes: 01c8f1c44b83 ("mm, dax, gpu: convert vm_insert_mixed to pfn_t")
> Cc: Dave Hansen <dave@xxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Reported-by: Julian Margetson <runaway@xxxxxxxx>
> Reported-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> mm/memory.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 30991f83d0bf..93ce37989471 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1591,10 +1591,15 @@ int vm_insert_mixed(struct vm_area_struct *vma,
> unsigned long addr,
> * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
> * without pte special, it would there be refcounted as a normal page.
> */
> - if (!HAVE_PTE_SPECIAL && pfn_t_valid(pfn)) {
> + if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
> struct page *page;
>
> - page = pfn_t_to_page(pfn);
> + /*
> + * At this point we are committed to insert_page()
> + * regardless of whether the caller specified flags that
> + * result in pfn_t_has_page() == false.
> + */
> + page = pfn_to_page(pfn_t_to_pfn(pfn));
> return insert_page(vma, addr, page, vma->vm_page_prot);
> }
> return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
>
>
>
> [ 16.503323] systemd[1]: Mounting FUSE Control File System...
> [ 42.703092] Oops: Machine check, sig: 7 [#1]
> [ 42.707624] PREEMPT Canyonlands
> [ 42.710959] Modules linked in:
> [ 42.714201] CPU: 0 PID: 553 Comm: Xorg Not tainted 4.5.0-rc1-Sam460ex #1
> [ 42.721283] task: ee1e45c0 ti: ecd46000 task.ti: ecd46000
> [ 42.726983] NIP: 1fed2480 LR: 1fed2404 CTR: 1fed24d0
> [ 42.732227] REGS: ecd47f10 TRAP: 0214 Not tainted (4.5.0-rc1-Sam460ex)
> [ 42.739395] MSR: 0002d000 <CE,EE,PR,ME> CR: 28004262 XER: 00000000
> [ 42.746244]
> GPR00: 1f396134 bfcb0970 b77fc6f0 b6fbeffc b67d5008 00000780 00000004
> 00000000
> GPR08: 00000000 b6fbeffc 00000000 bfcb0920 1fed2404 2076dff4 00000000
> 00000780
> GPR16: 00000000 00000020 00000000 00000000 00001e00 209be650 00000438
> b67d5008
> GPR24: 00000780 bfcb09c8 209a8728 b6fbf000 b6fbf000 b67d5008 1ffdaff4
> 00001e00
> [ 42.778096] NIP [1fed2480] 0x1fed2480
> [ 42.781967] LR [1fed2404] 0x1fed2404
> [ 42.785741] Call Trace:
> [ 42.943688] ---[ end trace 5d20a91d2d30d9d6 ]---
> [ 42.948311]
> [ 46.641774] Machine check in kernel mode.
> [ 46.645805] Data Write PLB Error
> [ 46.649031] Machine Check exception is imprecise
> [ 46.653658] Vector: 214 at [eccfbf10]
> [ 46.657408] pc: 1ffa9480
> [ 46.660325] lr: 1ffa9404
> [ 46.663241] sp: bf9252b0
> [ 46.666123] msr: 2d000
> [ 46.668746] current = 0xee1e73c0
> [ 46.672149] pid = 663, comm = Xorg
> [ 46.676074] Linux version 4.5.0-rc1-Sam460ex (root@julian-VirtualBox)
Ok, I think the patch is still needed for the issue Tomi reported,
this appears to be a separate bug.
Can you send me your kernel config?
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>