On Thu 14-11-19 21:53:27, John Hubbard wrote: > 1. Call the new global pin_user_pages_fast(), from pin_goldfish_pages(). > > 2. 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] > > Another side effect is that the release code is simplified because > the page[] loop is now in gup.c instead of here, so just delete the > local release_user_pages() entirely, and call > put_user_pages_dirty_lock() directly, instead. > > [1] https://lore.kernel.org/r/20190723153640.GB720@xxxxxx > > Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > drivers/platform/goldfish/goldfish_pipe.c | 17 +++-------------- > 1 file changed, 3 insertions(+), 14 deletions(-) > > diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c > index 7ed2a21a0bac..635a8bc1b480 100644 > --- a/drivers/platform/goldfish/goldfish_pipe.c > +++ b/drivers/platform/goldfish/goldfish_pipe.c > @@ -274,7 +274,7 @@ static int pin_goldfish_pages(unsigned long first_page, > *iter_last_page_size = last_page_size; > } > > - ret = get_user_pages_fast(first_page, requested_pages, > + ret = pin_user_pages_fast(first_page, requested_pages, > !is_write ? FOLL_WRITE : 0, > pages); > if (ret <= 0) > @@ -285,18 +285,6 @@ static int pin_goldfish_pages(unsigned long first_page, > return ret; > } > > -static void release_user_pages(struct page **pages, int pages_count, > - int is_write, s32 consumed_size) > -{ > - int i; > - > - for (i = 0; i < pages_count; i++) { > - if (!is_write && consumed_size > 0) > - set_page_dirty(pages[i]); > - put_page(pages[i]); > - } > -} > - > /* Populate the call parameters, merging adjacent pages together */ > static void populate_rw_params(struct page **pages, > int pages_count, > @@ -372,7 +360,8 @@ static int transfer_max_buffers(struct goldfish_pipe *pipe, > > *consumed_size = pipe->command_buffer->rw_params.consumed_size; > > - release_user_pages(pipe->pages, pages_count, is_write, *consumed_size); > + put_user_pages_dirty_lock(pipe->pages, pages_count, > + !is_write && *consumed_size > 0); > > mutex_unlock(&pipe->lock); > return 0; > -- > 2.24.0 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
