fsdax fix 5.1-rc6

- Avoid a crash scenario with architectures like powerpc that require
   'pgtable_deposit' for the zero page.
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Merge tag 'fsdax-fix-5.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull fsdax fix from Dan Williams:
 "A single filesystem-dax fix. It has been lingering in -next for a long
  while and there are no other fsdax fixes on the horizon:

   - Avoid a crash scenario with architectures like powerpc that require
     'pgtable_deposit' for the zero page"

* tag 'fsdax-fix-5.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  fs/dax: Deposit pagetable even when installing zero page
This commit is contained in:
Linus Torvalds 2019-04-15 15:10:20 -07:00
commit 5512320c9f

View File

@ -33,6 +33,7 @@
#include <linux/sizes.h>
#include <linux/mmu_notifier.h>
#include <linux/iomap.h>
#include <asm/pgalloc.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
@ -1407,7 +1408,9 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
unsigned long pmd_addr = vmf->address & PMD_MASK;
struct vm_area_struct *vma = vmf->vma;
struct inode *inode = mapping->host;
pgtable_t pgtable = NULL;
struct page *zero_page;
spinlock_t *ptl;
pmd_t pmd_entry;
@ -1422,12 +1425,22 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
DAX_PMD | DAX_ZERO_PAGE, false);
if (arch_needs_pgtable_deposit()) {
pgtable = pte_alloc_one(vma->vm_mm);
if (!pgtable)
return VM_FAULT_OOM;
}
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
if (!pmd_none(*(vmf->pmd))) {
spin_unlock(ptl);
goto fallback;
}
if (pgtable) {
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
mm_inc_nr_ptes(vma->vm_mm);
}
pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
pmd_entry = pmd_mkhuge(pmd_entry);
set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
@ -1436,6 +1449,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
return VM_FAULT_NOPAGE;
fallback:
if (pgtable)
pte_free(vma->vm_mm, pgtable);
trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry);
return VM_FAULT_FALLBACK;
}