On Wed, Feb 1, 2023 at 4:41 PM Xiao Ni <xni@xxxxxxxxxx> wrote: > > On Thu, Feb 2, 2023 at 8:23 AM Xiao Ni <xni@xxxxxxxxxx> wrote: > > > > On Thu, Feb 2, 2023 at 2:00 AM Song Liu <song@xxxxxxxxxx> wrote: > > > > > > On Wed, Feb 1, 2023 at 4:46 AM Xiao Ni <xni@xxxxxxxxxx> wrote: > > > > > > > > It has added io_acct_set for raid0/raid5 io accounting and it needs to > > > > alloc md_io_acct in the i/o path. They are free when the bios come back > > > > from member disks. Now we don't have a method to monitor if those bios > > > > are all come back. In the takeover process, it needs to free the raid0 > > > > memory resource including the memory pool for md_io_acct. But maybe some > > > > bios are still not returned. When those bios are returned, it can cause > > > > panic bcause of introducing NULL pointer or invalid address. Something > > > > like this: > > > > > > Can we use mddev->active_io for this? If not, please explain the reason > > > in the comments (in the code). > > > > Hi Song > > > > At first, we thought this way. Now ->acitve_io is used to wait all > > submit processes to exit. > > If we use ->active_io to count acct_bio, it means we change the usage > > of ->active_io. > > In mddev_suspend, first it waits for all submit processes to finish, > > then it calls ->quiesce > > to wait all inflight io to come back. For raid0, it's ok to use > > ->acitve_io to count acct_bio. > > But for raid5, not sure if it's ok. What's your opinion? > > Hi Song > > I've sent V4. If you think ->active_io is a better way to count acct_io, > I'll re-write the patch to use ->active_io I haven't thought about all the details. But we should try very hard to avoid adding another percpu_ref. So let's try to use active_io to count acct_io. Thanks, Song
