From: Trond Myklebust <trond.myklebust@hammerspace.com> stable inclusion from stable-v5.10.111 commit 4a2544ce244bd27825a940824d1084505188695a category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5GL1Z Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 3e17898aca293a24dae757a440a50aa63ca29671 ] If memory allocation triggers a direct reclaim from the state recovery thread, then we can deadlock. Use memalloc_nofs_save/restore to ensure that doesn't happen. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- fs/nfs/nfs4state.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index cbeec29e9f21..a8fe8f84c5ae 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -49,6 +49,7 @@ #include <linux/workqueue.h> #include <linux/bitops.h> #include <linux/jiffies.h> +#include <linux/sched/mm.h> #include <linux/sunrpc/clnt.h> @@ -2557,9 +2558,17 @@ static void nfs4_layoutreturn_any_run(struct nfs_client *clp) static void nfs4_state_manager(struct nfs_client *clp) { + unsigned int memflags; int status = 0; const char *section = "", *section_sep = ""; + /* + * State recovery can deadlock if the direct reclaim code tries + * start NFS writeback. So ensure memory allocations are all + * GFP_NOFS. + */ + memflags = memalloc_nofs_save(); + /* Ensure exclusive access to NFSv4 state */ do { trace_nfs4_state_mgr(clp); @@ -2654,6 +2663,7 @@ static void nfs4_state_manager(struct nfs_client *clp) clear_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state); } + memalloc_nofs_restore(memflags); nfs4_end_drain_session(clp); nfs4_clear_state_manager_bit(clp); @@ -2671,6 +2681,7 @@ static void nfs4_state_manager(struct nfs_client *clp) return; if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0) return; + memflags = memalloc_nofs_save(); } while (refcount_read(&clp->cl_count) > 1 && !signalled()); goto out_drain; @@ -2683,6 +2694,7 @@ static void nfs4_state_manager(struct nfs_client *clp) clp->cl_hostname, -status); ssleep(1); out_drain: + memalloc_nofs_restore(memflags); nfs4_end_drain_session(clp); nfs4_clear_state_manager_bit(clp); } -- 2.20.1