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From:   bugzilla-daemon@kernel.org
To:     linux-ext4@vger.kernel.org
Subject: [Bug 217965] New: ext4(?) regression since 6.5.0 on sata hdd
Date:   Mon, 02 Oct 2023 08:10:21 +0000
Message-ID: <bug-217965-13602@https.bugzilla.kernel.org/>
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https://bugzilla.kernel.org/show_bug.cgi?id=3D217965

            Bug ID: 217965
           Summary: ext4(?) regression since 6.5.0 on sata hdd
           Product: File System
           Version: 2.5
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: ext4
          Assignee: fs_ext4@kernel-bugs.osdl.org
          Reporter: iivanich@gmail.com
        Regression: No

Since kernel 6.5.x and 6.6-rc* I'm getting weird kworker flush activity when
building openwrt from sources.
91 root      20   0       0      0      0 R  99,7   0,0  18:06.57
kworker/u16:4+flush-8:16

Openwrt sources resides on the sata hdd drive with ext4 fs,I'm using this s=
etup
for a last 5 years, the problem is that since 6.5 kernels after the openwrt
kernel patch make
step(https://git.openwrt.org/?p=3Dopenwrt/openwrt.git;a=3Dblob;f=3Dscripts/=
patch-kernel.sh;h=3Dc2b7e7204952f93946a6075d546cbeae32c2627f;hb=3DHEAD
which probably involves a lot of copy and write operations)
kworker/u16:4+flush-8:16 uses 100% of one core for a while(5-15 minutes) ev=
en
after I canceling openwrt build.

I tried to move this openwrt sources folder to an ssd drive where my system=
 is
resides and run openwrt build from there and getting no issues with kworker
flush  cpu usage. Also I have no such behavior with 6.4.x and older kernels=
 so
it looks like regression to me, not sure if this is a fs, vfs or even block
subsystem issue.

This is how it looks in perf
Samples: 320K of event 'cycles:P', Event count (approx.): 363448649248
  Children      Self  Command          Shared Object=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
Symbol
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ret_from_fork_asm
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ret_from_fork
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
kthread
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
worker_thread
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
process_one_work
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
wb_workfn
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
wb_writeback
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
__writeback_inodes_wb
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
writeback_sb_inodes
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
__writeback_single_inode
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
do_writepages
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_writepages
+   12,40%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_do_writepages
+   12,39%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_map_blocks
+   12,39%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_ext_map_blocks
+   12,38%     0,00%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_mb_new_blocks
+   12,38%     0,93%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_mb_regular_allocator
+    9,42%     0,00%  cc1              [unknown]                           =
 [.]
0000000000000000
+    5,42%     0,53%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_mb_scan_aligned
+    4,88%     0,69%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
mb_find_extent
+    3,99%     3,95%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
mb_find_order_for_block
+    3,51%     0,61%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_mb_load_buddy_gfp
+    2,95%     0,01%  cc1              [kernel.vmlinux]                    =
 [k]
asm_exc_page_fault
+    2,67%     0,18%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
pagecache_get_page
+    2,41%     0,40%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
__filemap_get_folio
+    2,33%     2,10%  cc1              cc1                                 =
 [.]
cpp_get_token_1
+    2,12%     0,05%  cc1              [kernel.vmlinux]                    =
 [k]
exc_page_fault
+    2,07%     0,04%  cc1              [kernel.vmlinux]                    =
 [k]
do_user_addr_fault
+    1,81%     0,52%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
filemap_get_entry
     1,80%     1,71%  cc1              cc1                                 =
 [.]
ht_lookup_with_hash
+    1,77%     0,08%  cc1              [kernel.vmlinux]                    =
 [k]
handle_mm_fault
+    1,65%     0,14%  cc1              [kernel.vmlinux]                    =
 [k]
__handle_mm_fault
     1,60%     1,49%  cc1              cc1                                 =
 [.]
_cpp_lex_direct
+    1,54%     0,73%  kworker/u16:2+f  [kernel.vmlinux]                    =
 [k]
ext4_mb_good_group
+    1,49%     1,46%  cc1              cc1                                 =
 [.]
ggc_internal_alloc
+    1,28%     0,05%  cc1              [kernel.vmlinux]                    =
 [k]
do_anonymous_page
+    1,28%     0,04%  cc1              [kernel.vmlinux]                    =
 [k]
entry_SYSCALL_64

--=20
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