From 15eb77a07c714ac80201abd0a9568888bcee6276 Mon Sep 17 00:00:00 2001 From: Wu Fengguang Date: Tue, 17 Jan 2012 11:18:56 -0600 Subject: writeback: fix NULL bdi->dev in trace writeback_single_inode bdi_prune_sb() resets sb->s_bdi to default_backing_dev_info when the tearing down the original bdi. Fix trace_writeback_single_inode to use sb->s_bdi=default_backing_dev_info rather than bdi->dev=NULL for a teared down bdi. Cc: Reported-by: Rabin Vincent Tested-by: Rabin Vincent Signed-off-by: Wu Fengguang --- include/trace/events/writeback.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 8588a8918023..06d302ebcb72 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -426,7 +426,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template, TP_fast_assign( strncpy(__entry->name, - dev_name(inode->i_mapping->backing_dev_info->dev), 32); + dev_name(inode_to_bdi(inode)->dev), 32); __entry->ino = inode->i_ino; __entry->state = inode->i_state; __entry->dirtied_when = inode->dirtied_when; -- cgit v1.2.3 From 3310225dfc71a35a2cc9340c15c0e08b14b3c754 Mon Sep 17 00:00:00 2001 From: Wu Fengguang Date: Mon, 9 Jan 2012 11:53:50 -0600 Subject: lib: proportion: lower PROP_MAX_SHIFT to 32 on 64-bit kernel PROP_MAX_SHIFT should be set to <=32 on 64-bit box. This fixes two bugs in the below lines of bdi_dirty_limit(): bdi_dirty *= numerator; do_div(bdi_dirty, denominator); 1) divide error: do_div() only uses the lower 32 bit of the denominator, which may trimmed to be 0 when PROP_MAX_SHIFT > 32. 2) overflow: (bdi_dirty * numerator) could easily overflow if numerator used up to 48 bits, leaving only 16 bits to bdi_dirty Cc: Cc: Peter Zijlstra Reported-by: Ilya Tumaykin Tested-by: Ilya Tumaykin Signed-off-by: Wu Fengguang --- include/linux/proportions.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/proportions.h b/include/linux/proportions.h index ef35bb73f69b..26a8a4ed9b07 100644 --- a/include/linux/proportions.h +++ b/include/linux/proportions.h @@ -81,7 +81,11 @@ void prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl) * Limit the time part in order to ensure there are some bits left for the * cycle counter and fraction multiply. */ +#if BITS_PER_LONG == 32 #define PROP_MAX_SHIFT (3*BITS_PER_LONG/4) +#else +#define PROP_MAX_SHIFT (BITS_PER_LONG/2) +#endif #define PROP_FRAC_SHIFT (BITS_PER_LONG - PROP_MAX_SHIFT - 1) #define PROP_FRAC_BASE (1UL << PROP_FRAC_SHIFT) -- cgit v1.2.3 From 977b7e3a52a7421ad33a393a38ece59f3d41c2fa Mon Sep 17 00:00:00 2001 From: Wu Fengguang Date: Sat, 4 Feb 2012 20:54:03 -0600 Subject: writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue When a SD card is hot removed without umount, del_gendisk() will call bdi_unregister() without destroying/freeing it. This leaves the bdi in the bdi->dev = NULL, bdi->wb.task = NULL, bdi->bdi_list removed state. When sync(2) gets the bdi before bdi_unregister() and calls bdi_queue_work() after the unregister, trace_writeback_queue will be dereferencing the NULL bdi->dev. Fix it with a simple test for NULL. LKML-reference: http://lkml.org/lkml/2012/1/18/346 Cc: stable@kernel.org Reported-by: Rabin Vincent Tested-by: Namjae Jeon Signed-off-by: Wu Fengguang --- include/trace/events/writeback.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 06d302ebcb72..5973410e8f8c 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -47,7 +47,10 @@ DECLARE_EVENT_CLASS(writeback_work_class, __field(int, reason) ), TP_fast_assign( - strncpy(__entry->name, dev_name(bdi->dev), 32); + struct device *dev = bdi->dev; + if (!dev) + dev = default_backing_dev_info.dev; + strncpy(__entry->name, dev_name(dev), 32); __entry->nr_pages = work->nr_pages; __entry->sb_dev = work->sb ? work->sb->s_dev : 0; __entry->sync_mode = work->sync_mode; -- cgit v1.2.3