Description:
References:
 https://lwn.net/Articles/668718/
 https://bugzilla.redhat.com/show_bug.cgi?id=1360968
 https://bugzilla.kernel.org/show_bug.cgi?id=107301
Notes:
 bwh> The upstream fix (rewrite of mbcache) is too intrusive to backport.
 bwh> We will mitigate this with cond_resched() as suggested in comment 1
 bwh> on the bz.k.o bug report.  I didn't want to add the no_mbcache mount
 bwh> option as in comment 12 because it's a uAPI extension, but it has
 bwh> now been added upstream (commit cdb7ee4c6327) so I think it would be
 bwh> reasonable to add it to supported stable releases.
 bwh> The problem seems to have been introduced (or exacerbated) by commit
 bwh> 1f3e55fe02d1 in 3.15, which added a retry loop in mb_cache_entry_alloc().
Bugs:
upstream: released (4.6-rc1) [f9a61eb4e2471c56a63cd804c7474128138c38ac, 82939d7999dfc1f1998c4b1c12e2f19edbdff272, be0726d33cb8f411945884664924bed3cb8c70ee]
4.9-upstream-stable: N/A "Fixed before branch point"
3.16-upstream-stable: ignored "Too intrusive to backport"
3.2-upstream-stable: ignored "Too intrusive to backport, and seems to be minor issue"
sid: released (4.6.1-1)
4.9-stretch-security: N/A "Fixed before branching point"
3.16-jessie-security: ignored "Too intrusive to backport, but will be mitigated"
3.2-wheezy-security: ignored "Too intrusive to backport, and seems to be minor issue"