On Sun 24-11-19 20:20:09, John Hubbard wrote:
Convert from get_user_pages() to pin_user_pages().
As required by pin_user_pages(), release these pages via
put_user_page(). In this case, do so via put_user_pages_dirty_lock().
That has the side effect of calling set_page_dirty_lock(), instead of set_page_dirty(). This is probably more accurate.
As Christoph Hellwig put it, "set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off." [1]
- Release each page in mem->hpages[] (instead of mem->hpas[]), because
that is the array that pin_longterm_pages() filled in. This is more accurate and should be a little safer from a maintenance point of view.
Except that this breaks the code. hpages is unioned with hpas...
[1] https://lore.kernel.org/r/20190723153640.GB720@lst.de
Signed-off-by: John Hubbard jhubbard@nvidia.com
arch/powerpc/mm/book3s64/iommu_api.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c index 56cc84520577..196383e8e5a9 100644 --- a/arch/powerpc/mm/book3s64/iommu_api.c +++ b/arch/powerpc/mm/book3s64/iommu_api.c @@ -103,7 +103,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua, for (entry = 0; entry < entries; entry += chunk) { unsigned long n = min(entries - entry, chunk);
ret = get_user_pages(ua + (entry << PAGE_SHIFT), n,
ret = pin_user_pages(ua + (entry << PAGE_SHIFT), n, FOLL_WRITE | FOLL_LONGTERM, mem->hpages + entry, NULL);@@ -167,9 +167,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua, return 0; free_exit:
- /* free the reference taken */
- for (i = 0; i < pinned; i++)
put_page(mem->hpages[i]);
- /* free the references taken */
- put_user_pages(mem->hpages, pinned);
vfree(mem->hpas); kfree(mem); @@ -212,10 +211,9 @@ static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem) if (!page) continue;
if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)SetPageDirty(page);
put_user_pages_dirty_lock(&mem->hpages[i], 1,MM_IOMMU_TABLE_GROUP_PAGE_DIRTY);
And the dirtying condition is wrong here as well. Currently it is always true.
Honza