| Message ID | 1449179922-502-3-git-send-email-matthew.r.wilcox@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Thu, Dec 3, 2015 at 1:58 PM, Matthew Wilcox <matthew.r.wilcox@intel.com> wrote: > From: Matthew Wilcox <willy@linux.intel.com> > > When we need to bail at this point, we do not hold the mutex, so jumping > to the error path which will drop the mutex is the wrong approach. > Just return the fallback instead. This mostly reverts commit fd6b9f6393. > > Signed-off-by: Matthew Wilcox <willy@linux.intel.com> > --- > fs/dax.c | 18 ++++++------------ > 1 file changed, 6 insertions(+), 12 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 727af65..71ba5f7 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -581,28 +581,22 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, > /* Fall back to PTEs if we're going to COW */ > if (write && !(vma->vm_flags & VM_SHARED)) { > split_huge_page_pmd(vma, address, pmd); > - reason = "cow write"; > return VM_FAULT_FALLBACK; > } > + > /* If the PMD would extend outside the VMA */ > - if (pmd_addr < vma->vm_start) { > - reason = "vma start unaligned"; > - goto fallback; > - } > - if ((pmd_addr + PMD_SIZE) > vma->vm_end) { > - reason = "vma end unaligned"; > - goto fallback; > - } > + if (pmd_addr < vma->vm_start) > + return VM_FAULT_FALLBACK; > + if ((pmd_addr + PMD_SIZE) > vma->vm_end) > + return VM_FAULT_FALLBACK; > > pgoff = linear_page_index(vma, pmd_addr); > size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > if (pgoff >= size) > return VM_FAULT_SIGBUS; > /* If the PMD would cover blocks out of the file */ > - if ((pgoff | PG_PMD_COLOUR) >= size) { > - reason = "offset + huge page size > file size"; > + if ((pgoff | PG_PMD_COLOUR) >= size) > return VM_FAULT_FALLBACK; > - } > > memset(&bh, 0, sizeof(bh)); > block = (sector_t)pgoff << (PAGE_SHIFT - blkbits); Having the pmd setup failure reasons is still handy since we have no other indication . I'll fix this up to handle the lock correctly.
On Thu, Dec 3, 2015 at 6:27 PM, Dan Williams <dan.j.williams@intel.com> wrote: > On Thu, Dec 3, 2015 at 1:58 PM, Matthew Wilcox > <matthew.r.wilcox@intel.com> wrote: >> From: Matthew Wilcox <willy@linux.intel.com> >> >> When we need to bail at this point, we do not hold the mutex, so jumping >> to the error path which will drop the mutex is the wrong approach. >> Just return the fallback instead. This mostly reverts commit fd6b9f6393. >> >> Signed-off-by: Matthew Wilcox <willy@linux.intel.com> [..] > Having the pmd setup failure reasons is still handy since we have no > other indication . I'll fix this up to handle the lock correctly. Here's what I came up with... no control flow changes. https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git/commit/?h=libnvdimm-pending&id=fd6b9f639309774cbd6d0a02befe257711a84cfb
On Thu, Dec 3, 2015 at 6:57 PM, Dan Williams <dan.j.williams@intel.com> wrote: > On Thu, Dec 3, 2015 at 6:27 PM, Dan Williams <dan.j.williams@intel.com> wrote: >> On Thu, Dec 3, 2015 at 1:58 PM, Matthew Wilcox >> <matthew.r.wilcox@intel.com> wrote: >>> From: Matthew Wilcox <willy@linux.intel.com> >>> >>> When we need to bail at this point, we do not hold the mutex, so jumping >>> to the error path which will drop the mutex is the wrong approach. >>> Just return the fallback instead. This mostly reverts commit fd6b9f6393. >>> >>> Signed-off-by: Matthew Wilcox <willy@linux.intel.com> > [..] >> Having the pmd setup failure reasons is still handy since we have no >> other indication . I'll fix this up to handle the lock correctly. > > Here's what I came up with... no control flow changes. > > https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git/commit/?h=libnvdimm-pending&id=fd6b9f639309774cbd6d0a02befe257711a84cfb Ah, sorry should have sent the patch. kernel.org hadn't refreshed yet: https://git.kernel.org/cgit/linux/kernel/git/djbw/nvdimm.git/commit/?h=libnvdimm-pending&id=a6cea26fcbe0
diff --git a/fs/dax.c b/fs/dax.c index 727af65..71ba5f7 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -581,28 +581,22 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, /* Fall back to PTEs if we're going to COW */ if (write && !(vma->vm_flags & VM_SHARED)) { split_huge_page_pmd(vma, address, pmd); - reason = "cow write"; return VM_FAULT_FALLBACK; } + /* If the PMD would extend outside the VMA */ - if (pmd_addr < vma->vm_start) { - reason = "vma start unaligned"; - goto fallback; - } - if ((pmd_addr + PMD_SIZE) > vma->vm_end) { - reason = "vma end unaligned"; - goto fallback; - } + if (pmd_addr < vma->vm_start) + return VM_FAULT_FALLBACK; + if ((pmd_addr + PMD_SIZE) > vma->vm_end) + return VM_FAULT_FALLBACK; pgoff = linear_page_index(vma, pmd_addr); size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; if (pgoff >= size) return VM_FAULT_SIGBUS; /* If the PMD would cover blocks out of the file */ - if ((pgoff | PG_PMD_COLOUR) >= size) { - reason = "offset + huge page size > file size"; + if ((pgoff | PG_PMD_COLOUR) >= size) return VM_FAULT_FALLBACK; - } memset(&bh, 0, sizeof(bh)); block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);