This basically reverts 47def82672b3 (jbd2: Remove __GFP_NOFAIL from jbd2 layer). The deprecation of __GFP_NOFAIL was a bad choice because it led to open coding the endless loop around the allocator rather than removing the dependency on the non failing allocation. So the deprecation was a clear failure and the reality tells us that __GFP_NOFAIL is not even close to go away.
It is still true that __GFP_NOFAIL allocations are generally discouraged and new uses should be evaluated and an alternative (pre-allocations or reservations) should be considered but it doesn't make any sense to lie the allocator about the requirements. Allocator can take steps to help making a progress if it knows the requirements. Signed-off-by: Michal Hocko <[email protected]> Acked-by: David Rientjes <[email protected]> --- Hi, this has been posted few months ago (http://marc.info/?l=linux-mm&m=142530454419654&w=2) but it hasn't gone anywhere so I am reposting. I've just rebased it on top of the ext4/for-linus tree. It wasn't clear to me which branch should I use so I've just picked this one as it was one of the most recently updated. fs/jbd2/journal.c | 11 +---------- fs/jbd2/transaction.c | 20 +++++++------------- 2 files changed, 8 insertions(+), 23 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index b96bd8076b70..0bc333b4a594 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -371,16 +371,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction, */ J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in)); -retry_alloc: - new_bh = alloc_buffer_head(GFP_NOFS); - if (!new_bh) { - /* - * Failure is not an option, but __GFP_NOFAIL is going - * away; so we retry ourselves here. - */ - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto retry_alloc; - } + new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL); /* keep subsequent assertions sane */ atomic_set(&new_bh->b_count, 1); diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index ff2f2e6ad311..799242cecffb 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -278,22 +278,16 @@ static int start_this_handle(journal_t *journal, handle_t *handle, alloc_transaction: if (!journal->j_running_transaction) { + /* + * If __GFP_FS is not present, then we may be being called from + * inside the fs writeback layer, so we MUST NOT fail. + */ + if ((gfp_mask & __GFP_FS) == 0) + gfp_mask |= __GFP_NOFAIL; new_transaction = kmem_cache_zalloc(transaction_cache, gfp_mask); - if (!new_transaction) { - /* - * If __GFP_FS is not present, then we may be - * being called from inside the fs writeback - * layer, so we MUST NOT fail. Since - * __GFP_NOFAIL is going away, we will arrange - * to retry the allocation ourselves. - */ - if ((gfp_mask & __GFP_FS) == 0) { - congestion_wait(BLK_RW_ASYNC, HZ/50); - goto alloc_transaction; - } + if (!new_transaction) return -ENOMEM; - } } jbd_debug(3, "New handle %p going live.\n", handle); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
