On Thu 02-11-23 10:28:57, Mikulas Patocka wrote: > On Thu, 2 Nov 2023, Marek Marczykowski-Górecki wrote: > > On Tue, Oct 31, 2023 at 06:24:19PM +0100, Mikulas Patocka wrote: > > > > > > Hi > > > > > > > > I would like to ask you to try this patch. Revert the changes to "order" > > > > and "PAGE_ALLOC_COSTLY_ORDER" back to normal and apply this patch on a > > > > clean upstream kernel. > > > > > > > > Does it deadlock? > > > > > > > > There is a bug in dm-crypt that it doesn't account large pages in > > > > cc->n_allocated_pages, this patch fixes the bug. > > > > This patch did not help. > > > > > If the previous patch didn't fix it, try this patch (on a clean upstream > > > kernel). > > > > > > This patch allocates large pages, but it breaks them up into single-page > > > entries when adding them to the bio. > > > > But this does help. > > Thanks. So we can stop blaming the memory allocator and start blaming the > NVMe subsystem. ;-) > I added NVMe maintainers to this thread - the summary of the problem is: > In dm-crypt, we allocate a large compound page and add this compound page > to the bio as a single big vector entry. Marek reports that on his system > it causes deadlocks, the deadlocks look like a lost bio that was never > completed. When I chop the large compound page to individual pages in > dm-crypt and add bio vector for each of them, Marek reports that there are > no longer any deadlocks. So, we have a problem (either hardware or > software) that the NVMe subsystem doesn't like bio vectors with large > bv_len. This is the original bug report: > https://lore.kernel.org/stable/ZTNH0qtmint%2FzLJZ@mail-itl/ Actually, Ming Lei has already identified [1] that we are apparently looping in an endless retry loop in nvme_queue_rq(), always ending up the attempt with BLK_STS_RESOURCE. Honza [1] https://lore.kernel.org/all/ZUHE52SznRaZQxnG@fedora -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
