On Thu, 6 Apr 2023 15:05:22 -0700 Minchan Kim <minchan@xxxxxxxxxx> wrote: > On Thu, Apr 06, 2023 at 04:41:01PM +0200, Christoph Hellwig wrote: > > Currently nothing waits for the synchronous reads before accessing > > the data. Switch them to an on-stack bio and submit_bio_wait to > > make sure the I/O has actually completed when the work item has been > > flushed. This also removes the call to page_endio that would unlock > > a page that has never been locked. > > > > Drop the partial_io/sync flag, as chaining only makes sense for the > > asynchronous reads of the entire page. > > > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > > Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> > Acked-by: Minchan Kim <minchan@xxxxxxxxxx> > > So this fixes zram_rw_page + CONFIG_ZRAM_WRITEBACK feature on > ppc some arch where PAGE_SIZE is not 4K. > > IIRC, we didn't have any report since the writeback feature was > introduced. Then, we may skip having the fix into stable? Someone may develop such a use case in the future. And backporting this fix will be difficult, unless people backport all the other patches, which is also difficult. What are the user-visible effects of this bug? It sounds like it will give userspace access to unintialized kernel memory, which isn't good.
