On 3/27/17, David Sterba <dste...@suse.cz> wrote: > On Sat, Mar 25, 2017 at 09:48:28AM +0300, Denis Kirjanov wrote: >> On 3/25/17, Jeff Mahoney <je...@suse.com> wrote: >> > On 3/24/17 5:02 AM, Denis Kirjanov wrote: >> >> Hi guys, >> >> >> >> Looks like that current code does GFP_KERNEL allocation inside >> >> __link_block_group. >> >> the function invokes kobject_add and internally creates sysfs files >> >> with the GFP_KERNEL flag set. >> > >> > Yep, that's a bug. >> > >> >> But since do_chunk_alloc executes insides the btrfs transaction it's >> >> not allowed to sleep. >> > >> > It's allowed to sleep but isn't allowed to do reclaim that involves >> > file >> > system writeback. Michal Hocko's allocation context idea would fix >> > this, but it's not there yet, so we'll need to defer the kobject_add >> > until we can use GFP_KERNEL. >> >> Ok, I see. Can you point out to the initial patchset? > > https://lwn.net/Articles/716323/ > > Fixing this properly is a lot of work so we might need to add a > temporary workaround, as Jeff suggests, to move calling into sysfs to a > later time. >
Care to send a patch? Or I can dig a bit. Thanks!
