Am 07.11.2022 um 16:13 hat Hanna Reitz geschrieben: > Hi, > > v1 cover letter: > https://lists.nongnu.org/archive/html/qemu-block/2022-09/msg00389.html > > bdrv_replace_child_noperm() drains the child via > bdrv_parent_drained_{begin,end}_single(). When it removes a child, the > bdrv_parent_drained_end_single() at its end will be called on an empty > child, making the BDRV_POLL_WHILE() in it poll the main AioContext > (because c->bs is NULL). > > That’s wrong, though, because it’s supposed to operate on the parent. > bdrv_parent_drained_end_single_no_poll() will have scheduled any BHs in > the parents’ AioContext, which may be anything, not necessarily the main > context. Therefore, we must poll the parent’s context. > > Patch 3 does this for both bdrv_parent_drained_{begin,end}_single(). > Patch 1 ensures that we can legally call > bdrv_child_get_parent_aio_context() from those I/O context functions, > and patch 2 fixes blk_do_set_aio_context() to not cause an assertion > failure if it beginning a drain can end up in blk_get_aio_context() > before blk->ctx has been updated.
Hmm, I may have unintentionally made this series obsolete with the drain series I sent today. The poll instances that you're fixing simply don't exist any more after it. Can you check if the bug is gone with my series? I would hope so, but if not, we would probably need to apply a fix in a different place. Kevin
