On Tue, Jul 03, 2018 at 10:05:04AM -0700, Yang Shi wrote: > I'm not sure if it is a good choice to let filesystem handle such vital VM > regression. IMHO, writing out filesystem page from direct reclaim context is > a vital VM bug. It means something is definitely wrong in VM. It should > never happen. If it does happen, it should happen reliably; this isn't the sort of thing where some linked list had gotten corrupted. This would be a structural problem in the VM code. So presumably, if the WARN_ON triggered, it should be be noticed by VM developers, and they should fix it. In general, though, BUG_ON's should be avoided unless there really is no way to recover. > It sounds ok to have filesystem throw out warning and handle it, but I'm not > sure if someone will just ignore the warning, but it should *never* be > ignored. If a kernel develper (a VM developer in this case) ignores a warning, that's just simply professional malpractice. In general WARN_ON's should only be used as a sign of a kernel bug. So they should never be ignored. - Ted
