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On 2021/10/21 20:20, Zhengyuan Liu
wrote:
Maybe we can reproduce your issue as follows:On Thu, Oct 21, 2021 at 4:55 PM yebin <yebin10@xxxxxxxxxx> wrote:On 2021/10/21 16:03, Jan Kara wrote: On Thu 21-10-21 10:21:55, Zhengyuan Liu wrote: On Thu, Oct 21, 2021 at 1:37 AM Jan Kara <jack@xxxxxxx> wrote: On Wed 13-10-21 09:46:46, Zhengyuan Liu wrote: we are encounting following Mysql crash problem while importing tables : 2021-09-26T11:22:17.825250Z 0 [ERROR] [MY-013622] [InnoDB] [FATAL] fsync() returned EIO, aborting. 2021-09-26T11:22:17.825315Z 0 [ERROR] [MY-013183] [InnoDB] Assertion failure: ut0ut.cc:555 thread 281472996733168 At the same time , we found dmesg had following message: [ 4328.838972] Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O! [ 4328.850234] File: /data/mysql/data/sysbench/sbtest53.ibd PID: 625 Comm: kworker/42:1 Firstly, we doubled Mysql has operating the file with direct IO and buffered IO interlaced, but after some checking we found it did only do direct IO using aio. The problem is exactly from direct-io interface (__generic_file_write_iter) itself. ssize_t __generic_file_write_iter() { ... if (iocb->ki_flags & IOCB_DIRECT) { loff_t pos, endbyte; written = generic_file_direct_write(iocb, from); /* * If the write stopped short of completing, fall back to * buffered writes. Some filesystems do this for writes to * holes, for example. For DAX files, a buffered write will * not succeed (even if it did, DAX does not handle dirty * page-cache pages correctly). */ if (written < 0 || !iov_iter_count(from) || IS_DAX(inode)) goto out; status = generic_perform_write(file, from, pos = iocb->ki_pos); ... } >From above code snippet we can see that direct io could fall back to buffered IO under certain conditions, so even Mysql only did direct IO it could interleave with buffered IO when fall back occurred. I have no idea why FS(ext3) failed the direct IO currently, but it is strange __generic_file_write_iter make direct IO fall back to buffered IO, it seems breaking the semantics of direct IO. The reproduced environment is: Platform: Kunpeng 920 (arm64) Kernel: V5.15-rc PAGESIZE: 64K Mysql: V8.0 Innodb_page_size: default(16K) Thanks for report. I agree this should not happen. How hard is this to reproduce? Any idea whether the fallback to buffered IO happens because iomap_dio_rw() returns -ENOTBLK or because it returns short write? It is easy to reproduce in my test environment, as I said in the previous email replied to Andrew this problem is related to kernel page size. Ok, can you share a reproducer? Can you post output of "dumpe2fs -h <device>" for the filesystem where the problem happens? Thanks! Sure, the output is: # dumpe2fs -h /dev/sda3 dumpe2fs 1.45.3 (14-Jul-2019) Filesystem volume name: <none> Last mounted on: /data Filesystem UUID: 09a51146-b325-48bb-be63-c9df539a90a1 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file Thanks for the data. OK, a filesystem without extents. Does your test by any chance try to do direct IO to a hole in a file? Because that is not (and never was) supported without extents. Also the fact that you don't see the problem with ext4 (which means extents support) would be pointing in that direction. Honza I try to reprodeuce this issue as follows, maybe this is just one scenario : step1: Modify kernel code, add delay in dio_complete and dio_bio_end_aio step2: mkfs.ext4 /dev/sda step3: mount /dev/sda /home/test step4: fio -filename=/home/test/test -direct=0 -buffered=1 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=4k -size=16k -numjobs=1 -name=test_r_w step5: fio -filename=/home/test/test -direct=1 -buffered=0 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=4k -size=4k -numjobs=1 -name=test_r_w & step6: fio -filename=/home/test/test -direct=0 -buffered=1 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=4k -size=16k -numjobs=1 -name=test_r_wHi, yebin Thanks for your test case, but it is not the same problem. The scenario you described here is some thing the kernel design for, since you are intending to interleave buffered IO and direct IO, please look at this two patch: 332391a (“fs: Fix page cache inconsistency when mixing buffered and AIO DIO”) 5a9d929 (“iomap: report collisions between directio and buffered writes to userspace”) 1. mkfs.ext4 -b 1024 /dev/sdb （PAGE_SIZE=4K） 2. mount /dev/sdb /home/test 3. fio -filename=/home/test/test -direct=0 -buffered=1 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=1k -size=4k -numjobs=1 -name=test_r_w 4. fio -filename=/home/test/test -direct=1 -buffered=0 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=1k -size=1k -numjobs=1 -name=test_r_w & 5. fio -filename=/home/test/test -direct=0 -buffered=1 -iodepth 1 -thread -rw=write -rwmixread=70 -ioengine=libaio -bs=1k -size=5k -offset=1024 -numjobs=1 -name=test_r_w As file system block size is 1K, there are 4 buffer_head per page. So direct IO and buffer IO maybe operate on the same page, although it does not operate on the same logical block. I add some debug information into kernel as follows: diff --git a/fs/direct-io.c b/fs/direct-io.c index ec7c7d1c0329..aebc3e76f8ca 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -38,6 +38,8 @@ #include <linux/atomic.h> #include <linux/prefetch.h> +#include <linux/delay.h> + /* * How many user pages to map in one call to get_user_pages(). This determines * the size of a structure in the slab cache @@ -224,20 +226,20 @@ static inline struct page *dio_get_page(struct dio *dio, */ void dio_warn_stale_pagecache(struct file *filp) { - static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); +// static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); char pathname[128]; struct inode *inode = file_inode(filp); char *path; errseq_set(&inode->i_mapping->wb_err, -EIO); - if (__ratelimit(&_rs)) { +// if (__ratelimit(&_rs)) { path = file_path(filp, pathname, sizeof(pathname)); if (IS_ERR(path)) path = "(unknown)"; pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n"); pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid, current->comm); - } +// } } /** @@ -305,15 +307,20 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags) * end_io() when necessary, otherwise a racing buffer read would cache * zeros from unwritten extents. */ + printk("%s: before invalidate page \n", __func__); + mdelay(10 * 1000); if (flags & DIO_COMPLETE_INVALIDATE && ret > 0 && dio->op == REQ_OP_WRITE && dio->inode->i_mapping->nrpages) { + printk("%s: start to call invalidate_inode_pages2_range nrpags=%lu\n", + __func__, dio->inode->i_mapping->nrpages); err = invalidate_inode_pages2_range(dio->inode->i_mapping, offset >> PAGE_SHIFT, (offset + ret - 1) >> PAGE_SHIFT); if (err) dio_warn_stale_pagecache(dio->iocb->ki_filp); } + printk("%s: end invalidate page \n", __func__); inode_dio_end(dio->inode); diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 21b0fc0d6ffe..35d1a330437b 100644 --- a/fs/ext4/file.c + printk("%s: end invalidate page \n", __func__); inode_dio_end(dio->inode); diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 21b0fc0d6ffe..35d1a330437b 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -241,6 +241,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) inode_lock(inode); } + printk("%s: start lock inode offset=%llu \n", __func__, iocb->ki_pos); ret = ext4_write_checks(iocb, from); if (ret <= 0) goto out; @@ -278,7 +279,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret == -EIOCBQUEUED && unaligned_aio) ext4_unwritten_wait(inode); inode_unlock(inode); - + printk("%s: unlock inode\n", __func__); if (ret > 0) ret = generic_write_sync(iocb, ret); diff --git a/mm/truncate.c b/mm/truncate.c index 43c73db17a0a..9b1ffedf831b 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -677,6 +677,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping, int ret2 = 0; int did_range_unmap = 0; + printk("%s: start=%lu end=%lu pages=%lu\n", __func__, start, end, mapping->nrpages); if (mapping->nrpages == 0 && mapping->nrexceptional == 0) goto out; @@ -690,6 +691,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping, /* We rely upon deletion not changing page->index */ index = indices[i]; + printk("%s: index=%lu\n", __func__, index); if (index > end) break;
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