A new unit test for the device-dax 1GB enabling currently fails with
this warning before hanging the test thread:
WARNING: CPU: 0 PID: 21 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1e3/0x1f0
percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic
[..]
CPU: 0 PID: 21 Comm: rcuos/1 Tainted: G O 4.10.0-rc7-next-
20170207+ #944
[..]
Call Trace:
dump_stack+0x86/0xc3
__warn+0xcb/0xf0
warn_slowpath_fmt+0x5f/0x80
? rcu_nocb_kthread+0x27a/0x510
? dax_pmem_percpu_exit+0x50/0x50 [dax_pmem]
percpu_ref_switch_to_atomic_rcu+0x1e3/0x1f0
? percpu_ref_exit+0x60/0x60
rcu_nocb_kthread+0x339/0x510
? rcu_nocb_kthread+0x27a/0x510
kthread+0x101/0x140
The get_user_pages() path needs to arrange for references to be taken
against the dev_pagemap instance backing the pud mapping. Refactor the
existing __gup_device_huge_pmd() to also account for the pud case.
Link: http://lkml.kernel.org/r/148653181153.38226.9605457830505509385.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SetPageReferenced(page);
}
SetPageReferenced(page);
}
-static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+static int __gup_device_huge(unsigned long pfn, unsigned long addr,
unsigned long end, struct page **pages, int *nr)
{
int nr_start = *nr;
unsigned long end, struct page **pages, int *nr)
{
int nr_start = *nr;
- unsigned long pfn = pmd_pfn(pmd);
struct dev_pagemap *pgmap = NULL;
struct dev_pagemap *pgmap = NULL;
- pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
do {
struct page *page = pfn_to_page(pfn);
do {
struct page *page = pfn_to_page(pfn);
+static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+ unsigned long end, struct page **pages, int *nr)
+{
+ unsigned long fault_pfn;
+
+ fault_pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ return __gup_device_huge(fault_pfn, addr, end, pages, nr);
+}
+
+static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
+ unsigned long end, struct page **pages, int *nr)
+{
+ unsigned long fault_pfn;
+
+ fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+ return __gup_device_huge(fault_pfn, addr, end, pages, nr);
+}
+
static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
if (!pte_allows_gup(pud_val(pud), write))
return 0;
if (!pte_allows_gup(pud_val(pud), write))
return 0;
+
+ VM_BUG_ON(!pfn_valid(pud_pfn(pud)));
+ if (pud_devmap(pud))
+ return __gup_device_huge_pud(pud, addr, end, pages, nr);
+
/* hugepages are never "special" */
VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL);
/* hugepages are never "special" */
VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL);
- VM_BUG_ON(!pfn_valid(pud_pfn(pud)));
refs = 0;
head = pud_page(pud);
refs = 0;
head = pud_page(pud);