In the Linux kernel, the following vulnerability has been resolved: NFS: fix nfsreleasefolio() to not deadlock via kcompactd writeback Add PFKCOMPACTD flag and currentiskcompactd() helper to check for it so nfsreleasefolio() can skip calling nfswbfolio() from kcompactd. Otherwise NFS can deadlock waiting for kcompactd enduced writeback which recurses back to NFS (which triggers writeback to NFSD via NFS loopback mount on the same host, NFSD blocks waiting for XFS's call to _filemapgetfolio): 6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds. {--- [58] "kcompactd0" [<0>] foliowaitbit+0xe8/0x200 [<0>] foliowaitwriteback+0x2b/0x80 [<0>] nfswbfolio+0x80/0x1b0 [nfs] [<0>] nfsreleasefolio+0x68/0x130 [nfs] [<0>] splithugepagetolisttoorder+0x362/0x840 [<0>] migratepagesbatch+0x43d/0xb90 [<0>] migratepagessync+0x9a/0x240 [<0>] migratepages+0x93c/0x9f0 [<0>] compactzone+0x8e2/0x1030 [<0>] compactnode+0xdb/0x120 [<0>] kcompactd+0x121/0x2e0 [<0>] kthread+0xcf/0x100 [<0>] retfromfork+0x31/0x40 [<0>] retfromforkasm+0x1a/0x30 ---} [akpm@linux-foundation.org: fix build]