diff options
| author | Trond Myklebust <trond.myklebust@hammerspace.com> | 2022-01-29 13:32:45 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-15 14:18:35 +0200 |
| commit | 3f8f3a1c10e268df53b201a344b3277e0527ae3b (patch) | |
| tree | 27c2cc4d493862f1de61d825ae814140ac721547 /fs | |
| parent | 96cdf2fdbe89150fbdadccc62b4937accef701fa (diff) | |
NFSv4: Protect the state recovery thread against direct reclaim
[ 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>
Diffstat (limited to 'fs')
| -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 aa2caba38a01..1d2b81a233bb 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> @@ -2504,9 +2505,17 @@ static int nfs4_bind_conn_to_session(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 { clear_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state); @@ -2600,6 +2609,7 @@ 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); @@ -2616,6 +2626,7 @@ 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; @@ -2627,6 +2638,7 @@ 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); } |