1. 05 Aug, 2019 2 commits
    • Vivek Goyal's avatar
      dax: dax_layout_busy_page() should not unmap cow pages · d75996dd
      Vivek Goyal authored
      Vivek:
      
          "As of now dax_layout_busy_page() calls unmap_mapping_range() with last
           argument as 1, which says even unmap cow pages. I am wondering who needs
           to get rid of cow pages as well.
      
           I noticed one interesting side affect of this. I mount xfs with -o dax and
           mmaped a file with MAP_PRIVATE and wrote some data to a page which created
           cow page. Then I called fallocate() on that file to zero a page of file.
           fallocate() called dax_layout_busy_page() which unmapped cow pages as well
           and then I tried to read back the data I wrote and what I get is old
           data from persistent memory. I lost the data I had written. This
           read basically resulted in new fault and read back the data from
           persistent memory.
      
           This sounds wrong. Are there any users which need to unmap cow pages
           as well? If not, I am proposing changing it to not unmap cow pages.
      
           I noticed this while while writing virtio_fs code where when I tried
           to reclaim a memory range and that corrupted the executable and I
           was running from virtio-fs and program got segment violation."
      
      Dan:
      
          "In fact the unmap_mapping_range() in this path is only to synchronize
           against get_user_pages_fast() and force it to call back into the
           filesystem to re-establish the mapping. COW pages should be left
           untouched by dax_layout_busy_page()."
      
      Cc: <stable@vger.kernel.org>
      Fixes: 5fac7408 ("mm, fs, dax: handle layout changes to pinned dax mappings")
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Link: https://lore.kernel.org/r/20190802192956.GA3032@redhat.comSigned-off-by: default avatarDan Williams <dan.j.williams@intel.com>
      d75996dd
    • Linus Torvalds's avatar
      Linux 5.3-rc3 · e21a712a
      Linus Torvalds authored
      e21a712a
  2. 04 Aug, 2019 10 commits
  3. 03 Aug, 2019 28 commits