Message ID | 20190806063344.GA11184@xps-13 |
---|---|
State | New |
Headers | show |
Series | [SRU,B,PULL] bcache: fix hung task timeout in bch_bucket_alloc() | expand |
I'll send a new pull request with the additional changes from the last reviews. -Andrea On Tue, Aug 06, 2019 at 08:33:44AM +0200, Andrea Righi wrote: > BugLink: https://bugs.launchpad.net/bugs/1784665 > > [Impact] > > bcache_allocator can call the following: > > bch_allocator_thread() > -> bch_prio_write() > -> bch_bucket_alloc() > -> wait on &ca->set->bucket_wait > > But the wake up event on bucket_wait is supposed to come from > bch_allocator_thread() itself causing a deadlock. > > [Test Case] > > This is a simple script that can easily trigger the deadlock condition: > https://launchpadlibrarian.net/381282009/bcache-basic-repro.sh > > A better test case has been also provided in LP: #1796292: > https://bugs.launchpad.net/curtin/+bug/1796292/+attachment/5280353/+files/curtin-nvme.sh > > [Fix] > > Fix by making the call to bch_prio_write() non-blocking, so that > bch_allocator_thread() never waits on itself. Moreover, make sure to > wake up the garbage collector thread when bch_prio_write() is failing to > allocate buckets to increase the chance of freeing up more buckets. > > In addition to that it would be safer to also import other upstream > bcache fixes (all clean cherry picks): > > 7e865eba00a3df2dc8c4746173a8ca1c1c7f042e bcache: fix potential deadlock in cached_def_free() > 80265d8dfd77792e133793cef44a21323aac2908 bcache: acquire bch_register_lock later in cached_dev_free() > ce4c3e19e5201424357a0c82176633b32a98d2ec bcache: Replace bch_read_string_list() by __sysfs_match_string() > ecb37ce9baac653cc09e2b631393dde3df82979f bcache: Move couple of functions to sysfs.c > 04cbc21137bfa4d7b8771a5b14f3d6c9b2aee671 bcache: Move couple of string arrays to sysfs.c > 5f2b18ec8e1643410a2369f06888951cdedea0bf bcache: Fix a compiler warning in bcache_device_init() > 20d3a518713e394efa5a899c84574b4b79ec5098 bcache: Reduce the number of sparse complaints about lock imbalances > 42361469ae84c851e40cb1f94c8c9a14cdd94039 bcache: Suppress more warnings about set-but-not-used variables > f0d3814090ac77de94c42b7124c37ece23629197 bcache: Remove an unused variable > 47344e330eabc1515cbe6061eb337100a3ab6d37 bcache: Fix kernel-doc warnings > 9dfbdec7b7fea1ff1b7b5d5d12980dbc7dca46c7 bcache: Annotate switch fall-through > 4a4e443835a43a79113cc237c472c0d268eb1e1c bcache: Add __printf annotation to __bch_check_keys() > fd01991d5c20098c5c1ffc4dca6c821cc60a2f74 bcache: Fix indentation > ca71df31661a0518ed58a1a59cf1993962153ebb bcache: fix using of loop variable in memory shrink > f3641c3abd1da978ee969b0203b71b86ec1bfa93 bcache: fix error return value in memory shrink > 688892b3bc05e25da94866e32210e5f503f16f69 bcache: fix incorrect sysfs output value of strip size > 09a44ca2114737e0932257619c16a2b50c7807f1 bcache: use pr_info() to inform duplicated CACHE_SET_IO_DISABLE set > c4dc2497d50d9c6fb16aa0d07b6a14f3b2adb1e0 bcache: fix high CPU occupancy during journal > a728eacbbdd229d1d903e46261c57d5206f87a4a bcache: add journal statistic > 616486ab52ab7f9739b066d958bdd20e65aefd74 bcache: fix writeback target calc on large devices > 1f0ffa67349c56ea54c03ccfd1e073c990e7411e bcache: only set BCACHE_DEV_WB_RUNNING when cached device attached > eb8cbb6df38f6e5124a3d5f1f8a3dbf519537c60 bcache: improve bcache_reboot() > 9951379b0ca88c95876ad9778b9099e19a95d566 bcache: never writeback a discard operation > > [Regression Potential] > > The upstream fixes are all clean cherry picks from stable (most of them > are small cleanups), so regression potential is minimal. > > The only special patch is "UBUNTU: SAUCE: bcache: fix deadlock in > bcache_allocator" that is addressing the main deadlock bug (that seems > to be a mainline bug - not fixed yet). We should spend more time trying > to reproduce this deadlock with a mainline kernel and post the patch to > the LKML for review / feedback. > > However, considering that this patch seems to fix/prevent the specific > deadlock problem reported in this bug (tested on the affected platform), > it should be considered safe to apply it as it is for now, to prevent > potential hung task timeout conditions. > > --- > The following changes since commit face6017552c1e768188d512724720838be6d8c5: > > Revert "ovl: set I_CREATING on inode being created" (2019-08-06 01:13:14 -0400) > > are available in the Git repository at: > > git://git.launchpad.net/~arighi/+git/bionic-linux bcache-fix > > for you to fetch changes up to 177e9156ee68080d5cc8f352a7ab86cb5caeaa85: > > UBUNTU: SAUCE: bcache: fix deadlock in bcache_allocator (2019-08-06 08:31:17 +0200) > > ---------------------------------------------------------------- > Andrea Righi (1): > UBUNTU: SAUCE: bcache: fix deadlock in bcache_allocator > > Andy Shevchenko (3): > bcache: Move couple of string arrays to sysfs.c > bcache: Move couple of functions to sysfs.c > bcache: Replace bch_read_string_list() by __sysfs_match_string() > > Bart Van Assche (8): > bcache: Fix indentation > bcache: Add __printf annotation to __bch_check_keys() > bcache: Annotate switch fall-through > bcache: Fix kernel-doc warnings > bcache: Remove an unused variable > bcache: Suppress more warnings about set-but-not-used variables > bcache: Reduce the number of sparse complaints about lock imbalances > bcache: Fix a compiler warning in bcache_device_init() > > Coly Li (5): > bcache: improve bcache_reboot() > bcache: only set BCACHE_DEV_WB_RUNNING when cached device attached > bcache: use pr_info() to inform duplicated CACHE_SET_IO_DISABLE set > bcache: acquire bch_register_lock later in cached_dev_free() > bcache: fix potential deadlock in cached_def_free() > > Daniel Axtens (1): > bcache: never writeback a discard operation > > Michael Lyle (1): > bcache: fix writeback target calc on large devices > > Tang Junhui (5): > bcache: add journal statistic > bcache: fix high CPU occupancy during journal > bcache: fix incorrect sysfs output value of strip size > bcache: fix error return value in memory shrink > bcache: fix using of loop variable in memory shrink > > drivers/md/bcache/alloc.c | 5 ++- > drivers/md/bcache/bcache.h | 10 ++++-- > drivers/md/bcache/bset.c | 4 +-- > drivers/md/bcache/bset.h | 5 +-- > drivers/md/bcache/btree.c | 15 +++++---- > drivers/md/bcache/closure.c | 8 ++--- > drivers/md/bcache/extents.c | 2 -- > drivers/md/bcache/journal.c | 56 +++++++++++++++++++++++--------- > drivers/md/bcache/request.c | 1 + > drivers/md/bcache/super.c | 57 +++++++++++++++----------------- > drivers/md/bcache/sysfs.c | 75 +++++++++++++++++++++++++++++++++++-------- > drivers/md/bcache/util.c | 60 +++++++++------------------------- > drivers/md/bcache/util.h | 7 ++-- > drivers/md/bcache/writeback.c | 35 +++++++++++++++++--- > drivers/md/bcache/writeback.h | 12 ++++++- > 15 files changed, 215 insertions(+), 137 deletions(-)