On Mon, Jun 05 2017, Shaohua Li wrote: > On Mon, Jun 05, 2017 at 04:49:39PM +1000, Neil Brown wrote: >> >> If mddev_suspend() races with md_write_start() we can deadlock >> with mddev_suspend() waiting for the request that is currently >> in md_write_start() to complete the ->make_request() call, >> and md_write_start() waiting for the metadata to be updated >> to mark the array as 'dirty'. >> As metadata updates done by md_check_recovery() only happen then >> the mddev_lock() can be claimed, and as mddev_suspend() is often >> called with the lock held, these threads wait indefinitely for each >> other. >> >> We fix this by having md_write_start() abort if mddev_suspend() >> is happening, and ->make_request() aborts if md_write_start() >> aborted. >> md_make_request() can detect this abort, decrease the ->active_io >> count, and wait for mddev_suspend(). > > Applied the two patches, thanks! For this one, I added md_start_write symbol back. Will > push these to Linus in the 4.12 cycle. > Thanks for fixing the md_start_write export! At one stage in development I made it "static", but then forgot the export when I put it back :-( Thanks, NeilBrown
Attachment:
signature.asc
Description: PGP signature
