On 2016/2/23 15:02, He YunLei wrote: > On 2016/2/23 13:44, Chao Yu wrote: >> Hi Yunlei, > Hi Chao, >> >>> -----Original Message----- >>> From: Yunlei He [mailto:heyun...@huawei.com] >>> Sent: Tuesday, February 23, 2016 12:08 PM >>> To: chao2...@samsung.com; jaeg...@kernel.org; >>> linux-f2fs-devel@lists.sourceforge.net >>> Cc: bintian.w...@huawei.com; Yunlei He; Biao He >>> Subject: [f2fs-dev] [PATCH] f2fs: avoid hungtask problem caused by losing >>> wake_up >>> >>> The D state of wait_on_all_pages_writeback should be waken by >>> function f2fs_write_end_io when all writeback pages have been >>> succesfully written to device. It's possible that wake_up comes >>> between get_pages and io_schedule. Maybe in this case it will >>> lost wake_up and still in D state even if all pages have been >>> write back to device, and finally, the whole system will be into >>> the hungtask state. >> >> I haven't encountered such issue so far, do you suffer this in real >> world? >> > yes, I have encounter it, the whole file system is blocked at function > wait_on_all_pages_writeback beyond 120s when write cp, and no error reported > by storage device driver.
Hi YunLei Interesting... How to prove the page isn't been locked by storage block layer which doesn't finish the related bio? I suffer that case before, but then I solve it by seting a timer to break my mmc driver while missing some important interrupts(chip problem) for data-transfer to finish the io queue by mmcqd. Another thing, why making 5HZ for timeout? why not 10HZ ,15HZ... io_schedule_timeout(5*HZ); >>> >>> if (!get_pages(sbi, F2FS_WRITEBACK)) >>> break; >>> <--------- wake_up >> >> wake_up will put all tasks linked in sbi->cp_wait on run-queue, so >> here it should be save to call io_schedule, after being rescheduled, >> it will get the chance to check above condition to break out. >> >> Thanks, > > Here, we just doubt something weird may cause wait_on_all_pages_writeback > could not be waken. Wake_up trigger only one time by last bio's end_io > function, if the thread happen to miss it, the thread will be in D state > forever. So we change the code to make wait_on_all_pages_writeback awaken > periodically, then check the condition. > >> >>> io_schedule(); >>> >>> Signed-off-by: Yunlei He <heyun...@huawei.com> >>> Signed-off-by: Biao He <hebi...@huawei.com> >>> --- >>> fs/f2fs/checkpoint.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >>> index 2bac8a1..f55355d 100644 >>> --- a/fs/f2fs/checkpoint.c >>> +++ b/fs/f2fs/checkpoint.c >>> @@ -920,7 +920,7 @@ static void wait_on_all_pages_writeback(struct >>> f2fs_sb_info *sbi) >>> if (!get_pages(sbi, F2FS_WRITEBACK)) >>> break; >>> >>> - io_schedule(); >>> + io_schedule_timeout(5*HZ); >>> } >>> finish_wait(&sbi->cp_wait, &wait); >>> } >>> -- >>> 1.9.1 >> >> >> >> . >> > > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. Signup Now! > http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
