From b56ff9d397cecdaad6c98c9d57cc6fea475e1f50 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 8 Nov 2010 13:49:33 -0500 Subject: [PATCH] ext4: Don't call sb_issue_discard() in ext4_free_blocks() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Commit 5c521830cf (ext4: Support discard requests when running in no-journal mode) attempts to add sb_issue_discard() for data blocks (in data=writeback mode) and in no-journal mode. Unfortunately, this no longer works, because in commit dd3932eddf (block: remove BLKDEV_IFL_WAIT), sb_issue_discard() only presents a synchronous interface, and there are times when we call ext4_free_blocks() when we are are holding a spinlock, or are otherwise in an atomic context. For now, I've removed the call to sb_issue_discard() to prevent a deadlock or (if spinlock debugging is enabled) failures like this: BUG: scheduling while atomic: rc.sysinit/1376/0x00000002 Pid: 1376, comm: rc.sysinit Not tainted 2.6.36-ARCH #1 Call Trace: [] __schedule_bug+0x5e/0x70 [] schedule+0x950/0xa70 [] ? insert_work+0x7d/0x90 [] ? queue_work_on+0x1d/0x30 [] ? queue_work+0x37/0x60 [] schedule_timeout+0x21d/0x360 [] ? generic_make_request+0x2c3/0x540 [] wait_for_common+0xc0/0x150 [] ? default_wake_function+0x0/0x10 [] ? submit_bio+0x7c/0x100 [] ? wake_bit_function+0x0/0x40 [] wait_for_completion+0x18/0x20 [] blkdev_issue_discard+0x1b9/0x210 [] ext4_free_blocks+0x68e/0xb60 [] ? __ext4_handle_dirty_metadata+0x110/0x120 [] ext4_ext_truncate+0x8cc/0xa70 [] ? pagevec_lookup+0x1e/0x30 [] ext4_truncate+0x178/0x5d0 [] ? unmap_mapping_range+0xab/0x280 [] vmtruncate+0x56/0x70 [] ext4_setattr+0x14b/0x460 [] notify_change+0x194/0x380 [] do_truncate+0x60/0x90 [] ? security_inode_permission+0x1a/0x20 [] ? tomoyo_path_truncate+0x11/0x20 [] do_last+0x5d9/0x770 [] do_filp_open+0x1ed/0x680 [] ? page_fault+0x1f/0x30 [] ? alloc_fd+0xec/0x140 [] do_sys_open+0x61/0x120 [] sys_open+0x1b/0x20 [] system_call_fastpath+0x16/0x1b https://bugzilla.kernel.org/show_bug.cgi?id=22302 Reported-by: Mathias Burén Signed-off-by: "Theodore Ts'o" Cc: jiayingz@google.com --- fs/ext4/mballoc.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index c58eba34724a..5b4d4e3a4d58 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4640,8 +4640,6 @@ do_more: * with group lock held. generate_buddy look at * them with group lock_held */ - if (test_opt(sb, DISCARD)) - ext4_issue_discard(sb, block_group, bit, count); ext4_lock_group(sb, block_group); mb_clear_bits(bitmap_bh->b_data, bit, count); mb_free_blocks(inode, &e4b, bit, count); -- 2.20.1