diff options
| author | Trond Myklebust <trond.myklebust@hammerspace.com> | 2022-01-29 13:32:45 -0500 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@hammerspace.com> | 2022-02-25 18:50:12 -0500 |
| commit | 3e17898aca293a24dae757a440a50aa63ca29671 (patch) | |
| tree | b1dfbeab0f379693af02ccd21e2fcbe9e6a590af /fs/nfs/nfs4state.c | |
| parent | ab22e2cbbccbcf65bed9524605ac5dacb89471e8 (diff) | |
NFSv4: Protect the state recovery thread against direct reclaim
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>
Diffstat (limited to 'fs/nfs/nfs4state.c')
| -rw-r--r-- | fs/nfs/nfs4state.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index f5a62c0d999b..0f4818627ef0 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> @@ -2560,9 +2561,17 @@ 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); @@ -2657,6 +2666,7 @@ 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); @@ -2674,6 +2684,7 @@ 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; @@ -2686,6 +2697,7 @@ out_error: clp->cl_hostname, -status); ssleep(1); out_drain: + memalloc_nofs_restore(memflags); nfs4_end_drain_session(clp); nfs4_clear_state_manager_bit(clp); } |