On 2019/4/18 下午8:27, Nikolay Borisov wrote: > > > On 18.04.19 г. 14:54 ч., Qu Wenruo wrote: > <snip> > >> >> Forgot to mention, for that method, I'll definitely keep the BUG_ON() on >> @prealloc. >> >> Just make the allocation part fall back to use fs_info->last_chance[] to >> grab a valid memory slot. > > Before you go and re-invent the wheel I will suggest you take a look at > the mempool api (include/linux/mempool.h). AFAIK it's purpose is to > exactly ensure memory allocations from it will not fail (depending on > how the pool is configured) Know that before. But should_fail_slab() will ignore GFP flags, thus it doesn't make sense in error injection case. Thanks, Qu > >> >> Thanks, >> Qu >> >>> >>> The main reason I'm doing such error injection test is to ensure write >>> time tree checker is not the cause of the lockup. >>> >>> Of course I can directly inject error into btrfs_check_leaf_full() and >>> btrfs_check_node(), and filter the stack to ensure it only happen in >>> write time, and that's already what I'm crafting, based on the bcc error >>> inject example and kprobe return value overriding. >>> >>> But it will never be a bad idea to explore what can go wrong. >>> And "always BUG_ON()" -> "good enough (TM)" already looks like a >>> improvement to me. >>> >>> Thanks, >>> Qu >>> >>
