| Message ID | 20241012071824.124468-1-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fstests: btrfs/002: fix the OOM caused by too large block size | expand |
looks good. Nits: > For 64K sector size, the BLKS is 512, and BLKS is 128 (one 64K sector). ^^ NBLKS > $FALLOC is the correct value of 64K (10K rounded up to 64K). > Not sure what you meant here. More below. > diff --git a/tests/btrfs/002 b/tests/btrfs/002 > index f223cc60..0c231b89 100755 > --- a/tests/btrfs/002 > +++ b/tests/btrfs/002 > @@ -70,19 +70,14 @@ _read_modify_write() > _fill_blk() > { > local FSIZE > - local BLKS > - local NBLK > - local FALLOC > - local WS > + local NEWSIZE > > for i in `find /$1 -type f` > do > FSIZE=`stat -t $i | cut -d" " -f2` > - BLKS=`stat -c "%B" $i` > - NBLK=`stat -c "%b" $i` > - FALLOC=$(($BLKS * $NBLK)) > - WS=$(($FALLOC - $FSIZE)) > - _ddt of=$i oseek=$FSIZE obs=$WS count=1 status=noxfer 2>/dev/null & > + NEWSIZE=$(( ($FSIZE + $blksize -1 ) / $blksize * $blksize )) Please add extra ( ) otherwise it is very confusing. NEWSIZE=$(( (($FSIZE + $blksize -1 ) / $blksize) * $blksize )) > + > + $XFS_IO_PROG -c "pwrite -i /dev/urandom $FSIZE $(( $NEWSIZE - $FSIZE ))" $i > /dev/null & Reviewed-by: Anand Jain <anand.jain@oracle.com> Thanks, Anand
在 2024/10/22 21:54, Anand Jain 写道: > > looks good. > Nits: > >> For 64K sector size, the BLKS is 512, and BLKS is 128 (one 64K sector). > ^^ NBLKS > >> $FALLOC is the correct value of 64K (10K rounded up to 64K). >> > > Not sure what you meant here. More below. I just mean the old $FALLOC value is 64K, which is correct. I didn't see anything confusing here, I was explaining each variable involved. > > >> diff --git a/tests/btrfs/002 b/tests/btrfs/002 >> index f223cc60..0c231b89 100755 >> --- a/tests/btrfs/002 >> +++ b/tests/btrfs/002 >> @@ -70,19 +70,14 @@ _read_modify_write() >> _fill_blk() >> { >> local FSIZE >> - local BLKS >> - local NBLK >> - local FALLOC >> - local WS >> + local NEWSIZE >> for i in `find /$1 -type f` >> do >> FSIZE=`stat -t $i | cut -d" " -f2` >> - BLKS=`stat -c "%B" $i` >> - NBLK=`stat -c "%b" $i` >> - FALLOC=$(($BLKS * $NBLK)) >> - WS=$(($FALLOC - $FSIZE)) >> - _ddt of=$i oseek=$FSIZE obs=$WS count=1 status=noxfer 2>/dev/ >> null & > > >> + NEWSIZE=$(( ($FSIZE + $blksize -1 ) / $blksize * $blksize )) > > > Please add extra ( ) otherwise it is very confusing. > > NEWSIZE=$(( (($FSIZE + $blksize -1 ) / $blksize) * $blksize )) I didn't see how it's confusing. It's the very basic round down, and I didn't see any kernel code doing extra () just for round down. Thanks, Qu > > > >> + >> + $XFS_IO_PROG -c "pwrite -i /dev/urandom $FSIZE $(( $NEWSIZE - >> $FSIZE ))" $i > /dev/null & > > > > Reviewed-by: Anand Jain <anand.jain@oracle.com> > > > Thanks, Anand
diff --git a/tests/btrfs/002 b/tests/btrfs/002 index f223cc60..0c231b89 100755 --- a/tests/btrfs/002 +++ b/tests/btrfs/002 @@ -70,19 +70,14 @@ _read_modify_write() _fill_blk() { local FSIZE - local BLKS - local NBLK - local FALLOC - local WS + local NEWSIZE for i in `find /$1 -type f` do FSIZE=`stat -t $i | cut -d" " -f2` - BLKS=`stat -c "%B" $i` - NBLK=`stat -c "%b" $i` - FALLOC=$(($BLKS * $NBLK)) - WS=$(($FALLOC - $FSIZE)) - _ddt of=$i oseek=$FSIZE obs=$WS count=1 status=noxfer 2>/dev/null & + NEWSIZE=$(( ($FSIZE + $blksize -1 ) / $blksize * $blksize )) + + $XFS_IO_PROG -c "pwrite -i /dev/urandom $FSIZE $(( $NEWSIZE - $FSIZE ))" $i > /dev/null & done wait $! } @@ -118,6 +113,7 @@ $BTRFS_UTIL_PROG subvolume create $firstvol > /dev/null || _fail "btrfs subvolum dirp=`mktemp -duq $firstvol/dir.XXXXXX` _populate_fs -n 1 -f 20 -d 10 -r $dirp -s 10 -c SNAPNAME=0 +blksize=$(_get_block_size $SCRATCH_MNT) _create_snap $firstvol _save_checksum $firstvol $tmp.sv1.sum _verify_checksum $SNAPNAME $tmp.sv1.sum
[BUG] When running the test case btrfs/002, with 64K page size and 64K sector size, and the VM doesn't have much memory (in my case 4G Vram), the test case will trigger OOM and fail: btrfs/002 4s ... [failed, exit status 1]- output mismatch (see /home/adam/xfstests-dev/results//btrfs/002.out.bad) --- tests/btrfs/002.out 2024-04-25 18:13:45.035555469 +0930 +++ /home/adam/xfstests-dev/results//btrfs/002.out.bad 2024-10-12 17:19:48.785156223 +1030 @@ -1,2 +1 @@ QA output created by 002 -Silence is golden ... The OOM is triggered by the dd process, and a lot of dd processes are using too much memory: dd invoked oom-killer: gfp_mask=0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), order=0, oom_score_adj=250 CPU: 0 UID: 0 PID: 185764 Comm: dd Not tainted 6.12.0-rc2-custom+ #76 Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 Tasks state (memory values in pages): [ pid ] uid tgid total_vm rss rss_anon rss_file rss_shmem pgtables_bytes swapents oom_score_adj name [ 185665] 0 185665 8688 3840 3840 0 0 458752 4832 250 dd [ 185672] 0 185672 8688 2432 2432 0 0 393216 5312 250 dd [ 185680] 0 185680 8688 2016 2016 0 0 458752 4960 250 dd [ 185686] 0 185686 8688 2080 2080 0 0 458752 3584 250 dd [ 185693] 0 185693 8688 2144 2144 0 0 458752 4384 250 dd [ 185700] 0 185700 8688 2176 2176 0 0 458752 3584 250 dd [ 185707] 0 185707 8688 1792 1792 0 0 524288 3616 250 dd [ 185714] 0 185714 8688 2304 2304 0 0 458752 3488 250 dd [ 185721] 0 185721 8688 1920 1920 0 0 458752 2624 250 dd [ 185728] 0 185728 8688 2272 2272 0 0 393216 2528 250 dd [ 185735] 0 185735 8688 2048 2048 0 0 393216 3552 250 dd [ 185742] 0 185742 8688 1984 1984 0 0 458752 2816 250 dd [ 185751] 0 185751 8688 1600 1600 0 0 458752 2784 250 dd [ 185756] 0 185756 8688 1120 1120 0 0 458752 2400 250 dd [ 185764] 0 185764 8688 1504 1504 0 0 393216 2240 250 dd [ 185772] 0 185772 8688 1504 1504 0 0 458752 1984 250 dd [ 185777] 0 185777 8688 1280 1280 0 0 393216 2336 250 dd [ 185784] 0 185784 8688 2144 2144 0 0 393216 2272 250 dd [ 185791] 0 185791 8688 2176 2176 0 0 458752 576 250 dd [ 185798] 0 185798 8688 1696 1696 0 0 458752 1536 250 dd [ 185806] 0 185806 8688 1728 1728 0 0 393216 544 250 dd [ 185815] 0 185815 8688 2240 2240 0 0 458752 0 250 dd [ 185819] 0 185819 8688 1504 1504 0 0 458752 384 250 dd [ 185826] 0 185826 8688 1536 1536 0 0 458752 160 250 dd [ 185833] 0 185833 8688 2944 2944 0 0 458752 64 250 dd [ 185838] 0 185838 8688 2400 2400 0 0 458752 0 250 dd [ 185847] 0 185847 8688 864 864 0 0 458752 0 250 dd [ 185853] 0 185853 8688 1088 1088 0 0 393216 0 250 dd [ 185860] 0 185860 8688 416 416 0 0 393216 0 250 dd [ 185867] 0 185867 8688 352 352 0 0 458752 0 250 dd [CAUSE] The test case workload _fill_blk() is going to fill the file to its block boundary. But the implementation is not taking larger blocks into consideration. FSIZE=`stat -t $i | cut -d" " -f2` BLKS=`stat -c "%B" $i` NBLK=`stat -c "%b" $i` FALLOC=$(($BLKS * $NBLK)) WS=$(($FALLOC - $FSIZE)) $FSIZE is the file size, $BLKS is the size of each reported block, $NBLK is the number of blocks the file takes, thus $FALLOC is the rounded up block size. For 64K sector size, the BLKS is 512, and BLKS is 128 (one 64K sector). $FALLOC is the correct value of 64K (10K rounded up to 64K). Then the problem comes to how the write is done: _ddt of=$i oseek=$FSIZE obs=$WS count=1 status=noxfer 2>/dev/null & Unfrotunately the above command is using output block size of 54K, and need to skip 10K * 54K bytes, resulting a file size of 540M. So far although it's not the correct intention, it's not yet causing problem. But during _append_file(), we further enlarge the file by: FSIZE=`stat -t $i | cut -d" " -f2` dd if=$X of=$i seek=1 bs=$FSIZE obs=$FSIZE count=1 status=noxfer 2>/dev/null & In above case, since the previous file is 540M size, the output block size will also be 540M, taking a lot of memory. Furthermore since the workload is run in background, we can have many dd processes taking up at least 540M, causing huge memory usage and trigger OOM. [FIX] The original code is already not doing what it should do, just get rid of the cursed dd command usage inside _fill_blk(), and use pwrite from xfs_io instead. Signed-off-by: Qu Wenruo <wqu@suse.com> --- tests/btrfs/002 | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-)