On Tuesday, 8 January 2019 13:32:20 GMT Mark Syms wrote:
> Hi,
>
> We've seen this in testing with 4.19.
>
> Full trace is at the bottom.
>
> Looking at the code though it looks like it will assert if the value of
> change is equal to the number of blocks currently allocated to the inode.
> Is this expected or should the assert be using >= instead of > ?
It's weirder. Looking at
static inline void gfs2_add_inode_blocks(struct inode *inode, s64 change)
{
gfs2_assert(GFS2_SB(inode), (change >= 0 || inode->i_blocks > -change));
change *= (GFS2_SB(inode)->sd_sb.sb_bsize/GFS2_BASIC_BLOCK);
inode->i_blocks += change;
}
where the BUG is happening, "inode->i_blocks" is counting of 512b blocks and
"change" is in units of whatever-the-superblock-said which will probably be
counting 4096b blocks, so the comparison makes no sense.
It should probably read
static inline void gfs2_add_inode_blocks(struct inode *inode, s64 change)
{
change *= (GFS2_SB(inode)->sd_sb.sb_bsize/GFS2_BASIC_BLOCK);
gfs2_assert(GFS2_SB(inode), (change >= 0 || inode->i_blocks >=
-change));
inode->i_blocks += change;
}
so I'll make a patch for that unless someone wants to correct me.
As for why it's triggering, given the current scale difference I can only
assume it's an attempt to remove blocks from something which has none left.
I'd suspect a boundary case in sweep_bh_for_rgrps().
(It *is* possible currently to remove 1 4096b block from something which has
8 512b blocks so you can get to the state of "inode->i_blocks == 0)" It would
only blow up all the time if you did a "mkfs.gfs2 -b 512" which I don't
imagine anyone does that often...)
> Thanks,
>
> Mark
>
> --------------
>
> 2018-12-24 00:07:03 UTC] [ 3366.209273] kernel BUG at fs/gfs2/inode.h:64!
[snip]
> [2018-12-24 00:07:03 UTC] [ 3366.209802] Call Trace:
> [2018-12-24 00:07:03 UTC] [ 3366.209835] punch_hole+0xf4f/0x10d0 [gfs2]
> [2018-12-24 00:07:03 UTC] [ 3366.209866] ? __switch_to_asm+0x40/0x70
> [2018-12-24 00:07:03 UTC] [ 3366.209907] ? __switch_to_asm+0x40/0x70
> [2018-12-24 00:07:03 UTC] [ 3366.209924] ? __switch_to_asm+0x40/0x70
> [2018-12-24 00:07:03 UTC] [ 3366.209949] ? punch_hole+0xb3e/0x10d0 [gfs2]
> [2018-12-24 00:07:03 UTC] [ 3366.209983] gfs2_evict_inode+0x57b/0x680 [gfs2]
> [2018-12-24 00:07:03 UTC] [ 3366.210036] ?
> __inode_wait_for_writeback+0x75/0xe0
> [2018-12-24 00:07:03 UTC] [ 3366.210066] ? gfs2_evict_inode+0x1c7/0x680
> [gfs2]
> [2018-12-24 00:07:03 UTC] [ 3366.210090] evict+0xc6/0x1a0
> [2018-12-24 00:07:03 UTC] [ 3366.210151] delete_work_func+0x60/0x70 [gfs2]
> [2018-12-24 00:07:03 UTC] [ 3366.210177] process_one_work+0x165/0x370
> [2018-12-24 00:07:03 UTC] [ 3366.210197] worker_thread+0x49/0x3e0
> [2018-12-24 00:07:03 UTC] [ 3366.210216] kthread+0xf8/0x130
> [2018-12-24 00:07:03 UTC] [ 3366.210235] ? rescuer_thread+0x310/0x310
> [2018-12-24 00:07:03 UTC] [ 3366.210284] ? kthread_bind+0x10/0x10
> [2018-12-24 00:07:04 UTC] [ 3366.210301] ret_from_fork+0x35/0x40
--
Tim Smith <tim.sm...@citrix.com>
