On 4/30/20 11:12 AM, Christian Borntraeger wrote: > On 29.04.20 18:07, Dave Hansen wrote: >> On 4/28/20 3:50 PM, Claudio Imbrenda wrote: >>> If a page is inaccesible and it is used for things like sendfile, then >>> the content of the page is not always touched, and can be passed >>> directly to a driver, causing issues. >>> >>> This patch fixes the issue by adding a call to arch_make_page_accessible >>> in page_cache_pipe_buf_confirm; this fixes the issue. >> I spent about 5 minutes putting together a patch: >> >> https://sr71.net/~dave/intel/accessible.patch > You only set the page flag for compound pages. that of course leaves a big pile > of pages marked a not accessible, thus explaining the sendto trace and all kind > of other random traces. Ahh, nice catch! That does explain an oddity or two that I saw. > What do you see when you also do the SetPageAccessible(page); > in the else page of prep_new_page (order == 0). > (I do get > 10000 of these non compound page allocs just during boot). Yes, I see the same thing. I updated the patch and double-checked that it triggers properly with a socket-based sendfile().
