Re: [PATCH v5 11/24] goldish_pipe: convert to pin_user_pages() and put_user_page()
From: Jan Kara <jack@suse.cz>
Date: 2019-11-18 12:01:56
Also in:
bpf, dri-devel, kvm, linux-block, linux-fsdevel, linux-kselftest, linux-media, linux-mm, linux-rdma, linuxppc-dev, lkml, netdev
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@lst.de (local) Reviewed-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza
quoted hunk ↗ jump to hunk
--- 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 [off-list ref] SUSE Labs, CR