| Message ID | b5e9ce7c8b9b1a41adaaac883b15bf63c58dff93.1496245064.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 05/31/17 23:41, David Sterba wrote: > 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> Thanks, Anand > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/compression.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > 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 @@ static struct list_head *find_workspace(int type) > 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); > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 @@ static struct list_head *find_workspace(int type) 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);
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. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/compression.c | 10 ++++++++++ 1 file changed, 10 insertions(+)