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| author | David Sterba <dsterba@suse.com> | 2017-05-31 17:14:56 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-06-19 18:26:02 +0200 |
| commit | fe30853307559c3ec237391507c2b395095aa151 (patch) | |
| tree | 9e996f1c131b3acba6b2a745be86094134c3a4ec /fs | |
| parent | adf0212396e3af238e25e7c54ecb2959f19def24 (diff) | |
| download | linux-stable-fe30853307559c3ec237391507c2b395095aa151.tar.gz linux-stable-fe30853307559c3ec237391507c2b395095aa151.tar.bz2 linux-stable-fe30853307559c3ec237391507c2b395095aa151.zip | |
btrfs: add memalloc_nofs protections around alloc_workspace callback
The workspaces are preallocated at the beginning where we can safely use
GFP_KERNEL, but in some cases the find_workspace might reach the
allocation again, now in a more restricted context when the bios or
pages are being compressed.
To avoid potential lockup when alloc_workspace -> vmalloc would silently
use the GFP_KERNEL, add the memalloc_nofs helpers around the critical
call site.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/compression.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index ba511dd454d5..39cd164e5a62 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -32,6 +32,7 @@ #include <linux/writeback.h> #include <linux/bit_spinlock.h> #include <linux/slab.h> +#include <linux/sched/mm.h> #include "ctree.h" #include "disk-io.h" #include "transaction.h" @@ -757,6 +758,7 @@ static struct list_head *find_workspace(int type) struct list_head *workspace; int cpus = num_online_cpus(); int idx = type - 1; + unsigned nofs_flag; struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws; spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock; @@ -786,7 +788,15 @@ again: atomic_inc(total_ws); spin_unlock(ws_lock); + /* + * Allocation helpers call vmalloc that can't use GFP_NOFS, so we have + * to turn it off here because we might get called from the restricted + * context of btrfs_compress_bio/btrfs_compress_pages + */ + nofs_flag = memalloc_nofs_save(); workspace = btrfs_compress_op[idx]->alloc_workspace(); + memalloc_nofs_restore(nofs_flag); + if (IS_ERR(workspace)) { atomic_dec(total_ws); wake_up(ws_wait); |