Hello, In one of the testcases, parallel async dio writes to a file generates large no. of extents (upto 2M or more), and then this file is cleaned up for running other I/O tests. In the process of deleting this file, soft lockup messages are observed. We believe this is happening due to kernel being busy in unmapping/freeing those extents as part of the transaction processing. This is similar observation with the same call stack which was also reported here [1]. I also tried the qemu-img bench testcase shared in [1], and I was able to reproduce the soft lockup with that on Power. Similarly another instance was reported where xfs reflink remapping path also saw a similar softlockup problem while iterating over a million extent entries. So as I understood from that discussion [1], that kernel is moving towards a new preemption model, but IIUC, it is still an ongoing work. Also IMHO, this is still a problem in upstream and in older stable kernels which we still do support and such a fix might still be necessary for them. This patch adds the cond_resched() to both xfs_bunmapi_range() and xfs_reflink_remap_blocks() functions. v3 -> v4: Remove cond_resched() from defer finish and add it to both the unmap range and reflink remap functions individually. v2 -> v3: Move cond_resched within xfs_defer_finish_noroll() loop Ritesh Harjani (IBM) (1): xfs: Add cond_resched to block unmap range and reflink remap path fs/xfs/libxfs/xfs_bmap.c | 1 + fs/xfs/xfs_reflink.c | 1 + 2 files changed, 2 insertions(+) -- 2.44.0
