In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: Fix a race to wake on NFS_LAYOUT_DRAIN We found a few different systems hung up in writeback waiting on the same page lock, and one task waiting on the NFS_LAYOUT_DRAIN bit in pnfs_update_layout(), however the pnfs_layout_hdr's plh_outstanding count was zero. It seems most likely that this is another race between the waiter and waker similar to commit ed0172af5d6f ("SUNRPC: Fix a race to wake a sync task"). Fix it up by applying the advised barrier.
https://git.kernel.org/stable/c/e4b13885e7ef1e64e45268feef1e5f0707c47e72
https://git.kernel.org/stable/c/c01776287414ca43412d1319d2877cbad65444ac
https://git.kernel.org/stable/c/8ca65fa71024a1767a59ffbc6a6e2278af84735e
https://git.kernel.org/stable/c/8846fd02c98da8b79e6343a20e6071be6f372180
https://git.kernel.org/stable/c/864a54c1243ed3ca60baa4bc492dede1361f4c83
https://git.kernel.org/stable/c/1f4da20080718f258e189a2c5f515385fa393da6
https://git.kernel.org/stable/c/08287df60bac5b008b6bcdb03053988335d3d282