On Sun, Feb 23, 2025 at 3:42 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Sat, Feb 22, 2025 at 11:59:53AM +0800, mawupeng wrote: > > > > > > On 2025/2/22 11:45, Matthew Wilcox wrote: > > > On Sat, Feb 22, 2025 at 10:46:17AM +0800, Wupeng Ma wrote: > > >> Digging into the source, we found that the swap entry is invalid due to > > >> unknown reason, and this lead to invalid swap_info_struct. Excessive log > > >> printing can fill up the prioritized log space, leading to the purging of > > >> originally valid logs and hindering problem troubleshooting. To make this > > >> more robust, kill this task. > > > > > > this seems like a very bad way to fix this problem > > > > Sure, It's a bad way to fix this. Just a proper way to make it more robust? > > Since it will produce lots of invalid and same log? > > We have a mechanism to prevent flooding the log: <linux/ratelimit.h>. > If you grep for 'ratelimit' in include, you'll see a number of > convenience functions exist; not sure whether you'll need to use the raw > ratelilmit stuff, or if you can just use one of the prepared ones. > IMHO, I really don’t think log flooding is the issue here; rather, we’re dealing with an endless page fault. For servers, that might mean server is unresponsive , for phones, they could be quickly running out of battery. It’s certainly better to identify the root cause, but it could be due to a bit-flip in DDR or memory corruption in the page table. Until we can properly fix it, the patch seems somewhat reasonable—the wrong application gets killed, it at least has a chance to be restarted by systemd, Android init, etc. A PTE pointing to a non-existent swap file and never being enabled clearly indicates something has gone seriously wrong - either a hardware issue or a kernel bug. At the very least, it warrants a WARN_ON_ONCE(), even after we identify and fix the root cause, as it still enhances the system's robustness. Gaoxu will certainly encounter the same problem if do_swap_page() executes earlier than swap_duplicate() where the PTE points to a non-existent swap file [1]. That means the phone will heat up quickly. [1] https://lore.kernel.org/linux-mm/e223b0e6ba2f4924984b1917cc717bd5@xxxxxxxxx/ Thanks Barry
