On Sat, 20 Jun 2020 09:45:42 +0200 Greg Kroah-Hartman wrote: > On Fri, Jun 19, 2020 at 04:17:34PM -0700, Jakub Kicinski wrote: > > Hi! > > > > I'm trying to use debugfs_create_u32_array() in drivers/net/netdevsim > > and it causes memory leaks: > > > > unreferenced object 0xffff8880546642a0 (size 16): > > comm "test_udp_tuns.s", pid 2146, jiffies 4294928368 (age 3772.435s) > > hex dump (first 16 bytes): > > 84 52 6a 4d 80 88 ff ff 04 00 00 00 f3 78 7e 89 .RjM.........x~. > > backtrace: > > [<000000006962a447>] debugfs_create_u32_array+0x3f/0x90 > > > > I can see that debugfs_create_u32_array() allocates a structure at > > create time that ends up assigned to inode->i_private, but I don't > > see it freed anywhere. > > > > Am I missing something? I'm pretty sure files get removed, cause the > > driver calls debugfs_remove_recursive() and no other file types leaks. > > Yeah, that's a bug, nice catch. The debugfs_create*() functions should > not allocate local memory as we can't know to free that memory when the > file is removed. > > Can you fix this up, or do you want me to? I only see one in-kernel > user of this, so it shouldn't be that tough to do so. The one user > never removes that file so that's why no one noticed this before.
Ah, I wasn't sure how to fix but since you say that create functions shouldn't allocate memory seems like the fix will be to make callers pass an equivalent of struct debugfs_blob_wrapper for u32. I'm happy to send a patch to that effect - I have a process question tho - I need this change in net-next, should I sent the patch to you? Can it still make it into 5.8 (debugfs -> Linus -> net -> net-next) or perhaps can it go via net-next since there is no de facto bug in 5.8?
