On Mon, Jan 22, 2024 at 05:30:18PM +0100, Eric Dumazet wrote: > On Mon, Jan 22, 2024 at 5:04 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > I'm disappointed to have no reaction from netdev so far. Let's see if a > > more exciting subject line evinces some interest. > > Hmm, perhaps some of us were enjoying their weekend ? I am all in favour of people taking time off! However the report came in on Friday at 9am UTC so it had been more than a work day for anyone anywhere in the world without response. > I don't really know what changed recently, all I know is that TCP zero > copy is for real network traffic. > > Real trafic uses order-0 pages, 4K at a time. > > If can_map_frag() needs to add another safety check, let's add it. So it's your opinion that people don't actually use sendfile() from a local file, and we can make this fail to zerocopy? That's good because I had a slew of questions about what expectations we had around cache coherency between pages mapped this way and write()/mmap() of the original file. If we can just disallow this, we don't need to have a discussion about it. > syzbot is usually quite good at bisections, was a bug origin found ? I have the impression that Huawei run syzkaller themselves without syzbot. I suspect this bug has been there for a good long time. Wonder why nobody's found it before; it doesn't seem complicated for a fuzzer to stumble into.
