| Message ID | 20190708124019.3374246-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: reduce stack usage for btrfsic_process_written_block | expand |
Looks good,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Thanks Arnd
On Mon, Jul 08, 2019 at 02:40:09PM +0200, Arnd Bergmann wrote: > btrfsic_process_written_block() cals btrfsic_process_metablock(), > which has a fairly large stack usage due to the btrfsic_stack_frame > variable. It also calls btrfsic_test_for_metadata(), which now > needs several hundreds of bytes for its SHASH_DESC_ON_STACK(). > > In some configurations, we end up with both functions on the > same stack, and gcc warns about the excessive stack usage that > might cause the available stack space to run out: > > fs/btrfs/check-integrity.c:1743:13: error: stack frame size of 1152 bytes in function 'btrfsic_process_written_block' [-Werror,-Wframe-larger-than=] > > Marking both child functions as noinline_for_stack helps because > this guarantees that the large variables are not on the same > stack frame. > > Fixes: d5178578bcd4 ("btrfs: directly call into crypto framework for checksumming") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Added to misc-next, thanks.
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c index 81a9731959a9..0b52ab4cb964 100644 --- a/fs/btrfs/check-integrity.c +++ b/fs/btrfs/check-integrity.c @@ -940,7 +940,7 @@ static void btrfsic_stack_frame_free(struct btrfsic_stack_frame *sf) kfree(sf); } -static int btrfsic_process_metablock( +static noinline_for_stack int btrfsic_process_metablock( struct btrfsic_state *state, struct btrfsic_block *const first_block, struct btrfsic_block_data_ctx *const first_block_ctx, @@ -1706,8 +1706,9 @@ static void btrfsic_dump_database(struct btrfsic_state *state) * Test whether the disk block contains a tree block (leaf or node) * (note that this test fails for the super block) */ -static int btrfsic_test_for_metadata(struct btrfsic_state *state, - char **datav, unsigned int num_pages) +static noinline_for_stack int btrfsic_test_for_metadata( + struct btrfsic_state *state, + char **datav, unsigned int num_pages) { struct btrfs_fs_info *fs_info = state->fs_info; SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
btrfsic_process_written_block() cals btrfsic_process_metablock(), which has a fairly large stack usage due to the btrfsic_stack_frame variable. It also calls btrfsic_test_for_metadata(), which now needs several hundreds of bytes for its SHASH_DESC_ON_STACK(). In some configurations, we end up with both functions on the same stack, and gcc warns about the excessive stack usage that might cause the available stack space to run out: fs/btrfs/check-integrity.c:1743:13: error: stack frame size of 1152 bytes in function 'btrfsic_process_written_block' [-Werror,-Wframe-larger-than=] Marking both child functions as noinline_for_stack helps because this guarantees that the large variables are not on the same stack frame. Fixes: d5178578bcd4 ("btrfs: directly call into crypto framework for checksumming") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- fs/btrfs/check-integrity.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)