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-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1821395 Title: fscache: jobs might hang when fscache disk is full Status in linux package in Ubuntu: Invalid Status in linux source package in Bionic: Fix Released Status in linux source package in Cosmic: Fix Released Bug description: [Impact] * fscache issue where jobs get hung when fscache disk is full. * trivial upstream fix; already applied in X/D, required in B/C: commit c5a94f434c82 ("fscache: fix race between enablement and dropping of object"). [Test Case] * Test kernel verified / regression-tested by reporter. * Apparently there's no simple test case, but these are the conditions to hit the problem: 1) The active dataset size is equal to the cache disk size. The application reads the data over and over again. 2) Disk is near full (90%+) 3) cachefilesd in userspace is trying to cull the old objects while new objects are being looked up. 4) new cachefiles are created and some fail with no disk space. 5) race in dropping object state machine and deferred lookup state machine causes the hang. 6) HUNG in fscache_wait_for_deferred_lookup for clear bit FSCACHE_COOKIE_LOOKING_UP cookie->flags. [Regression Potential] * Low; contained in fscache; no further fixes applied upstream. * This patch is applied in a stable tree (linux-4.4.y). [Original Description] An user reported an fscache issue where jobs get hung when the fscache disk is full. After investigation, it's been found to be an issue already reported/fixed upstream, by commit c5a94f434c82 ("fscache: fix race between enablement and dropping of object"). This patch is required in Bionic and Cosmic, and it's applied in Xenial (via stable) and Disco. Apparently there's no simple test case, but these are the conditions to hit the problem: 1) The active dataset size is equal to the cache disk size. The application reads the data over and over again. 2) Disk is near full (90%+) 3) cachefilesd in userspace is trying to cull the old objects while new objects are being looked up. 4) new cachefiles are created and some fail with no disk space. 5) race in dropping object state machine and deferred lookup state machine causes the hang. 6) HUNG in fscache_wait_for_deferred_lookup for clear bit FSCACHE_COOKIE_LOOKING_UP cookie->flags. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1821395/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
