| Message ID | 20200804161755.10100-1-willy@infradead.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Remove nrexceptional tracking | expand |
On Tue, 2020-08-04 at 17:17 +0100, Matthew Wilcox (Oracle) wrote: > We actually use nrexceptional for very little these days. It's a > constant > source of pain with the THP patches because we don't know how large a > shadow entry is, so either we have to ask the xarray how many indices > it covers, or store that information in the shadow entry (and reduce > the amount of other information in the shadow entry proportionally). > While tracking down the most recent case of "evict tells me I've got > the accounting wrong again", I wondered if it might not be simpler to > just remove it. So here's a patch set to do just that. I think each > of these patches is an improvement in isolation, but the combination > of > all four is larger than the sum of its parts. > > I'm running xfstests on this patchset right now. If one of the DAX > people could try it out, that'd be fantastic. > > Matthew Wilcox (Oracle) (4): > mm: Introduce and use page_cache_empty > mm: Stop accounting shadow entries > dax: Account DAX entries as nrpages > mm: Remove nrexceptional from inode Hi Matthew, I applied these on top of 5.8 and ran them through the nvdimm unit test suite, and saw some test failures. The first failing test signature is: + umount test_dax_mnt ./dax-ext4.sh: line 62: 15749 Segmentation fault umount $MNT FAIL dax-ext4.sh (exit status: 139) The line is: https://github.com/pmem/ndctl/blob/master/test/dax.sh#L79 And the failing umount happens right after 'run_test', which calls this: https://github.com/pmem/ndctl/blob/master/test/dax-pmd.c > > fs/block_dev.c | 2 +- > fs/dax.c | 8 ++++---- > fs/inode.c | 2 +- > include/linux/fs.h | 2 -- > include/linux/pagemap.h | 5 +++++ > mm/filemap.c | 15 --------------- > mm/truncate.c | 19 +++---------------- > mm/workingset.c | 1 - > 8 files changed, 14 insertions(+), 40 deletions(-) >
On Thu, 2020-08-06 at 19:44 +0000, Verma, Vishal L wrote: > > > > I'm running xfstests on this patchset right now. If one of the DAX > > people could try it out, that'd be fantastic. > > > > Matthew Wilcox (Oracle) (4): > > mm: Introduce and use page_cache_empty > > mm: Stop accounting shadow entries > > dax: Account DAX entries as nrpages > > mm: Remove nrexceptional from inode > > Hi Matthew, > > I applied these on top of 5.8 and ran them through the nvdimm unit test > suite, and saw some test failures. The first failing test signature is: > > + umount test_dax_mnt > ./dax-ext4.sh: line 62: 15749 Segmentation fault umount $MNT > FAIL dax-ext4.sh (exit status: 139) > > The line is: https://github.com/pmem/ndctl/blob/master/test/dax.sh#L79 > And the failing umount happens right after 'run_test', which calls this: > https://github.com/pmem/ndctl/blob/master/test/dax-pmd.c > > And here is the associated kernel splat: [ 89.570142] EXT4-fs (pmem4): DAX enabled. Warning: EXPERIMENTAL, use at your own risk [ 89.573407] EXT4-fs (pmem4): mounted filesystem with ordered data mode. Opts: dax [ 90.450644] Injecting memory failure for pfn 0x148900 at process virtual address 0x7f2ec9b00000 [ 90.452421] Memory failure: 0x148900: Sending SIGBUS to dax-pmd:16886 due to hardware memory corruption [ 90.454067] Memory failure: 0x148900: recovery action for dax page: Recovered [ 91.656624] ------------[ cut here ]------------ [ 91.657822] kernel BUG at fs/inode.c:530! [ 91.658850] invalid opcode: 0000 [#1] SMP PTI [ 91.659883] CPU: 4 PID: 16891 Comm: umount Tainted: G O 5.8.0-00004-g6161e2d6ac48 #38 [ 91.661861] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 91.664920] RIP: 0010:clear_inode+0x78/0x90 [ 91.665934] Code: 00 a8 20 74 2b a8 40 75 29 48 8b 93 f0 01 00 00 48 8d 83 f0 01 00 00 48 39 c2 75 18 48 c7 83 e0 00 00 00 60 00 00 00 5b 5d c3 <0f> 0b 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b 66 66 2e 0f 1f 84 00 00 00 00 [ 91.669979] RSP: 0018:ffffc9000212fd98 EFLAGS: 00010002 [ 91.671151] RAX: 0000000000000004 RBX: ffff88810e33d470 RCX: 8c6318c6318c6319 [ 91.672689] RDX: ffff888110b48040 RSI: 0000000000000004 RDI: 0000000000000046 [ 91.674208] RBP: ffff88810e33d6b8 R08: 0000000000000000 R09: 0000000000000001 [ 91.675760] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88810e33d6b0 [ 91.677332] R13: ffff88811014c828 R14: ffff88811014c9c0 R15: ffff88810e3398c0 [ 91.678940] FS: 00007f86a7e74c80(0000) GS:ffff888117c00000(0000) knlGS:0000000000000000 [ 91.680745] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 91.682001] CR2: 000055bcfb4c3008 CR3: 0000000110b7c000 CR4: 00000000000006e0 [ 91.683581] Call Trace: [ 91.684268] ext4_clear_inode+0x16/0x80 [ 91.685298] ext4_evict_inode+0x5f/0x610 [ 91.686245] evict+0xcf/0x1f0 [ 91.687017] dispose_list+0x48/0x70 [ 91.687937] evict_inodes+0x152/0x190 [ 91.688918] generic_shutdown_super+0x37/0x100 [ 91.689880] kill_block_super+0x21/0x50 [ 91.690784] deactivate_locked_super+0x36/0xa0 [ 91.691790] cleanup_mnt+0x12d/0x190 [ 91.692658] task_work_run+0x5c/0xa0 [ 91.694739] __prepare_exit_to_usermode+0x1b6/0x1c0 [ 91.695806] do_syscall_64+0x5e/0xb0 [ 91.696656] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 91.697798] RIP: 0033:0x7f86a80c694b [ 91.698650] Code: 15 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 90 f3 0f 1e fa 31 f6 e9 05 00 00 00 0f 1f 44 00 00 f3 0f 1e fa b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1d 15 0c 00 f7 d8 64 89 01 48 [ 91.702545] RSP: 002b:00007ffd49a8cb98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 [ 91.704204] RAX: 0000000000000000 RBX: 00007f86a81ee204 RCX: 00007f86a80c694b [ 91.705732] RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000055bcfb4bf2a0 [ 91.707207] RBP: 000055bcfb4bafa0 R08: 0000000000000000 R09: 00007f86a8188a40 [ 91.708809] R10: 000055bcfb4c1550 R11: 0000000000000246 R12: 0000000000000000 [ 91.710040] R13: 000055bcfb4bf2a0 R14: 000055bcfb4bb0b0 R15: 000055bcfb4bb1d0 [ 91.711193] Modules linked in: nd_e820(O) nd_blk(O) nfit(O) kmem nd_pmem(O) nd_btt(O) dax_pmem(O) dax_pmem_core(O) libnvdimm(O) device_dax(O) nfit_test_iomap(O) [last unloaded: nfit_test_iomap] [ 91.714154] ---[ end trace 016cb116e8654993 ]--- [ 91.715011] RIP: 0010:clear_inode+0x78/0x90 [ 91.715803] Code: 00 a8 20 74 2b a8 40 75 29 48 8b 93 f0 01 00 00 48 8d 83 f0 01 00 00 48 39 c2 75 18 48 c7 83 e0 00 00 00 60 00 00 00 5b 5d c3 <0f> 0b 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b 66 66 2e 0f 1f 84 00 00 00 00 [ 91.718950] RSP: 0018:ffffc9000212fd98 EFLAGS: 00010002 [ 91.719976] RAX: 0000000000000004 RBX: ffff88810e33d470 RCX: 8c6318c6318c6319 [ 91.721187] RDX: ffff888110b48040 RSI: 0000000000000004 RDI: 0000000000000046 [ 91.722473] RBP: ffff88810e33d6b8 R08: 0000000000000000 R09: 0000000000000001 [ 91.723633] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88810e33d6b0 [ 91.724838] R13: ffff88811014c828 R14: ffff88811014c9c0 R15: ffff88810e3398c0 [ 91.726109] FS: 00007f86a7e74c80(0000) GS:ffff888117c00000(0000) knlGS:0000000000000000 [ 91.727575] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 91.728596] CR2: 000055bcfb4c3008 CR3: 0000000110b7c000 CR4: 00000000000006e0 [ 91.729794] note: umount[16891] exited with preempt_count 1 [ 91.730746] BUG: sleeping function called from invalid context at include/linux/percpu-rwsem.h:49 [ 91.732304] in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 16891, name: umount [ 91.733764] INFO: lockdep is turned off. [ 91.734476] irq event stamp: 6192 [ 91.735067] hardirqs last enabled at (6191): [<ffffffff81c7a974>] _raw_spin_unlock_irq+0x24/0x40 [ 91.736641] hardirqs last disabled at (6192): [<ffffffff81c7ab27>] _raw_spin_lock_irq+0x17/0x80 [ 91.738141] softirqs last enabled at (6120): [<ffffffff8134b3b8>] bdi_split_work_to_wbs+0x248/0x580 [ 91.739752] softirqs last disabled at (6116): [<ffffffff81347a5d>] wb_queue_work+0x4d/0x180 [ 91.741297] CPU: 4 PID: 16891 Comm: umount Tainted: G D O 5.8.0-00004-g6161e2d6ac48 #38 [ 91.742940] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 91.744887] Call Trace: [ 91.745401] dump_stack+0x92/0xc8 [ 91.745987] ___might_sleep.cold+0xb6/0xc6 [ 91.746716] exit_signals+0x1c/0x2d0 [ 91.747355] do_exit+0xc0/0xba0 [ 91.747942] ? __prepare_exit_to_usermode+0x1b6/0x1c0 [ 91.748821] rewind_stack_do_exit+0x17/0x20 [ 91.749619] RIP: 0033:0x7f86a80c694b [ 91.750330] Code: 15 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 90 f3 0f 1e fa 31 f6 e9 05 00 00 00 0f 1f 44 00 00 f3 0f 1e fa b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1d 15 0c 00 f7 d8 64 89 01 48 [ 91.753544] RSP: 002b:00007ffd49a8cb98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 [ 91.754902] RAX: 0000000000000000 RBX: 00007f86a81ee204 RCX: 00007f86a80c694b [ 91.756176] RDX: ffffffffffffff78 RSI: 0000000000000000 RDI: 000055bcfb4bf2a0 [ 91.757746] RBP: 000055bcfb4bafa0 R08: 0000000000000000 R09: 00007f86a8188a40 [ 91.759034] R10: 000055bcfb4c1550 R11: 0000000000000246 R12: 0000000000000000 [ 91.760166] R13: 000055bcfb4bf2a0 R14: 000055bcfb4bb0b0 R15: 000055bcfb4bb1d0
On Thu, Aug 06, 2020 at 08:16:02PM +0000, Verma, Vishal L wrote: > On Thu, 2020-08-06 at 19:44 +0000, Verma, Vishal L wrote: > > > > > > I'm running xfstests on this patchset right now. If one of the DAX > > > people could try it out, that'd be fantastic. > > > > > > Matthew Wilcox (Oracle) (4): > > > mm: Introduce and use page_cache_empty > > > mm: Stop accounting shadow entries > > > dax: Account DAX entries as nrpages > > > mm: Remove nrexceptional from inode > > > > Hi Matthew, > > > > I applied these on top of 5.8 and ran them through the nvdimm unit test > > suite, and saw some test failures. The first failing test signature is: > > > > + umount test_dax_mnt > > ./dax-ext4.sh: line 62: 15749 Segmentation fault umount $MNT > > FAIL dax-ext4.sh (exit status: 139) Thanks. Fixed: +++ b/fs/dax.c @@ -644,7 +644,7 @@ static int __dax_invalidate_entry(struct address_space *mapping, goto out; dax_disassociate_entry(entry, mapping, trunc); xas_store(&xas, NULL); - mapping->nrpages -= dax_entry_order(entry); + mapping->nrpages -= 1UL << dax_entry_order(entry); ret = 1; out: put_unlocked_entry(&xas, entry); Updated git tree at https://git.infradead.org/users/willy/pagecache.git/ It survives an xfstests run on an fsdax namespace which supports 2MB pages.
On Thu, 2020-10-08 at 20:33 +0100, Matthew Wilcox wrote: > On Thu, Aug 06, 2020 at 08:16:02PM +0000, Verma, Vishal L wrote: > > On Thu, 2020-08-06 at 19:44 +0000, Verma, Vishal L wrote: > > > > I'm running xfstests on this patchset right now. If one of the DAX > > > > people could try it out, that'd be fantastic. > > > > > > > > Matthew Wilcox (Oracle) (4): > > > > mm: Introduce and use page_cache_empty > > > > mm: Stop accounting shadow entries > > > > dax: Account DAX entries as nrpages > > > > mm: Remove nrexceptional from inode > > > > > > Hi Matthew, > > > > > > I applied these on top of 5.8 and ran them through the nvdimm unit test > > > suite, and saw some test failures. The first failing test signature is: > > > > > > + umount test_dax_mnt > > > ./dax-ext4.sh: line 62: 15749 Segmentation fault umount $MNT > > > FAIL dax-ext4.sh (exit status: 139) > > Thanks. Fixed: > > +++ b/fs/dax.c > @@ -644,7 +644,7 @@ static int __dax_invalidate_entry(struct address_space *mapping, > goto out; > dax_disassociate_entry(entry, mapping, trunc); > xas_store(&xas, NULL); > - mapping->nrpages -= dax_entry_order(entry); > + mapping->nrpages -= 1UL << dax_entry_order(entry); > ret = 1; > out: > put_unlocked_entry(&xas, entry); > > Updated git tree at > https://git.infradead.org/users/willy/pagecache.git/ I ran this tree through the unit tests, and everything passes. (Well, while the tests passed, this tree as-is did have an RCU warning splat. I rebased to v5.9-rc8 and that was fine). Feel free to add: Tested-by: Vishal Verma <vishal.l.verma@intel.com>