7:13 a.m.
Hi Hillf,
[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url:
https://github.com/0day-ci/linux/commits/Hillf-Danton/writeback-add-elast...
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 7.4.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=sh
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp(a)intel.com>
All errors (new ones prefixed by >>):
fs/fs-writeback.c: In function 'wbc_detach_inode':
> fs/fs-writeback.c:637:27: error: 'struct bdi_writeback'
has no member named 'bdp_waitq'
if
(waitqueue_active(&wb->bdp_waitq))
^~
In file included from include/linux/mmzone.h:10:0,
from include/linux/gfp.h:6,
from include/linux/slab.h:15,
from fs/fs-writeback.c:20:
fs/fs-writeback.c:638:19: error: 'struct bdi_writeback' has no member named
'bdp_waitq'
wake_up_all(&wb->bdp_waitq);
^
include/linux/wait.h:210:36: note: in definition of macro 'wake_up_all'
#define wake_up_all(x) __wake_up(x, TASK_NORMAL, 0, NULL)
^
vim +637 fs/fs-writeback.c
586
587 /**
588 * wbc_detach_inode - disassociate wbc from inode and perform foreign detection
589 * @wbc: writeback_control of the just finished writeback
590 *
591 * To be called after a writeback attempt of an inode finishes and undoes
592 * wbc_attach_and_unlock_inode(). Can be called under any context.
593 *
594 * As concurrent write sharing of an inode is expected to be very rare and
595 * memcg only tracks page ownership on first-use basis severely confining
596 * the usefulness of such sharing, cgroup writeback tracks ownership
597 * per-inode. While the support for concurrent write sharing of an inode
598 * is deemed unnecessary, an inode being written to by different cgroups at
599 * different points in time is a lot more common, and, more importantly,
600 * charging only by first-use can too readily lead to grossly incorrect
601 * behaviors (single foreign page can lead to gigabytes of writeback to be
602 * incorrectly attributed).
603 *
604 * To resolve this issue, cgroup writeback detects the majority dirtier of
605 * an inode and transfers the ownership to it. To avoid unnnecessary
606 * oscillation, the detection mechanism keeps track of history and gives
607 * out the switch verdict only if the foreign usage pattern is stable over
608 * a certain amount of time and/or writeback attempts.
609 *
610 * On each writeback attempt, @wbc tries to detect the majority writer
611 * using Boyer-Moore majority vote algorithm. In addition to the byte
612 * count from the majority voting, it also counts the bytes written for the
613 * current wb and the last round's winner wb (max of last round's current
614 * wb, the winner from two rounds ago, and the last round's majority
615 * candidate). Keeping track of the historical winner helps the algorithm
616 * to semi-reliably detect the most active writer even when it's not the
617 * absolute majority.
618 *
619 * Once the winner of the round is determined, whether the winner is
620 * foreign or not and how much IO time the round consumed is recorded in
621 * inode->i_wb_frn_history. If the amount of recorded foreign IO time is
622 * over a certain threshold, the switch verdict is given.
623 */
624 void wbc_detach_inode(struct writeback_control *wbc)
625 {
626 struct bdi_writeback *wb = wbc->wb;
627 struct inode *inode = wbc->inode;
628 unsigned long avg_time, max_bytes, max_time;
629 u16 history;
630 int max_id;
631
632 if (!wb)
633 return;
634
635 if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) &&
636 IS_ENABLED(CONFIG_CGWB_BDP_WITH_EBDI))
637 if (waitqueue_active(&wb->bdp_waitq))
638 wake_up_all(&wb->bdp_waitq);
639
640 history = inode->i_wb_frn_history;
641 avg_time = inode->i_wb_frn_avg_time;
642
643 /* pick the winner of this round */
644 if (wbc->wb_bytes >= wbc->wb_lcand_bytes &&
645 wbc->wb_bytes >= wbc->wb_tcand_bytes) {
646 max_id = wbc->wb_id;
647 max_bytes = wbc->wb_bytes;
648 } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) {
649 max_id = wbc->wb_lcand_id;
650 max_bytes = wbc->wb_lcand_bytes;
651 } else {
652 max_id = wbc->wb_tcand_id;
653 max_bytes = wbc->wb_tcand_bytes;
654 }
655
656 /*
657 * Calculate the amount of IO time the winner consumed and fold it
658 * into the running average kept per inode. If the consumed IO
659 * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for
660 * deciding whether to switch or not. This is to prevent one-off
661 * small dirtiers from skewing the verdict.
662 */
663 max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) <<
WB_FRN_TIME_SHIFT,
664 wb->avg_write_bandwidth);
665 if (avg_time)
666 avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) -
667 (avg_time >> WB_FRN_TIME_AVG_SHIFT);
668 else
669 avg_time = max_time; /* immediate catch up on first run */
670
671 if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) {
672 int slots;
673
674 /*
675 * The switch verdict is reached if foreign wb's consume
676 * more than a certain proportion of IO time in a
677 * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot
678 * history mask where each bit represents one sixteenth of
679 * the period. Determine the number of slots to shift into
680 * history from @max_time.
681 */
682 slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT),
683 (unsigned long)WB_FRN_HIST_MAX_SLOTS);
684 history <<= slots;
685 if (wbc->wb_id != max_id)
686 history |= (1U << slots) - 1;
687
688 if (history)
689 trace_inode_foreign_history(inode, wbc, history);
690
691 /*
692 * Switch if the current wb isn't the consistent winner.
693 * If there are multiple closely competing dirtiers, the
694 * inode may switch across them repeatedly over time, which
695 * is okay. The main goal is avoiding keeping an inode on
696 * the wrong wb for an extended period of time.
697 */
698 if (hweight32(history) > WB_FRN_HIST_THR_SLOTS)
699 inode_switch_wbs(inode, max_id);
700 }
701
702 /*
703 * Multiple instances of this function may race to update the
704 * following fields but we don't mind occassional inaccuracies.
705 */
706 inode->i_wb_frn_winner = max_id;
707 inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX);
708 inode->i_wb_frn_history = history;
709
710 wb_put(wbc->wb);
711 wbc->wb = NULL;
712 }
713 EXPORT_SYMBOL_GPL(wbc_detach_inode);
714
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