This makes sure printk format strings contain no more than a single
line.

Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
---
 mm/page_alloc.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1a8c595..96f0b33 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -198,13 +198,15 @@ static inline int bad_range(struct zone *zone, struct page *page)
 
 static void bad_page(struct page *page)
 {
-	printk(KERN_EMERG "Bad page state in process '%s'\n"
-		KERN_EMERG "page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n"
-		KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
-		KERN_EMERG "Backtrace:\n",
-		current->comm, page, (int)(2*sizeof(unsigned long)),
-		(unsigned long)page->flags, page->mapping,
+	printk(KERN_EMERG "Bad page state in process '%s'\n", current->comm);
+	printk(KERN_EMERG
+		"page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n",
+		page, (int) (2 * sizeof(unsigned long)),
+		(unsigned long) page->flags, page->mapping,
 		page_mapcount(page), page_count(page));
+	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n");
+	printk(KERN_EMERG "Backtrace:\n");
+
 	dump_stack();
 	page->flags &= ~(1 << PG_lru	|
 			1 << PG_private |
@@ -1575,13 +1577,13 @@ void show_free_areas(void)
 		}
 	}
 
-	printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu unstable:%lu\n"
-		" free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
+	printk("Active:%lu inactive:%lu dirty:%lu writeback:%lu unstable:%lu\n",
 		global_page_state(NR_ACTIVE),
 		global_page_state(NR_INACTIVE),
 		global_page_state(NR_FILE_DIRTY),
 		global_page_state(NR_WRITEBACK),
-		global_page_state(NR_UNSTABLE_NFS),
+		global_page_state(NR_UNSTABLE_NFS));
+	printk(" free:%lu slab:%lu mapped:%lu pagetables:%lu bounce:%lu\n",
 		global_page_state(NR_FREE_PAGES),
 		global_page_state(NR_SLAB_RECLAIMABLE) +
 			global_page_state(NR_SLAB_UNRECLAIMABLE),
-- 
1.5.2.4



-

[ message continues ]

I don't understand the reason for this change.

-

[ message continues ]

I'm sorry :). It helps to make one line per call only, since this
allows changing the printk internals for the better by reducing some
complexity. I believe this is a good thing. I have a patch that
changes printk, but it assumes that each format string only contains a
single line. Is this a very bad assumption to make? Or maybe I should
have sent that change first and made a reference to it?

But don't you also agree, on the grounds of principle, that a single
line per call is better style?

Vegard
-

[ message continues ]

Well we do multiple-lines-per-printk in rather a lot of places and it has
two advantages:

- less text size (I expect)

- the printk is "atomic" in that the logically-connected output lines
  won't get tangled up with an intervening printk from another CPU, or from
  an interrupt handler on this CPU.

Those are pretty modest advantages and I guess we could live without them
if we got a significant gain from doing so.  But it'd take quite some
effort hunting down all the callsites, and preventing new ones from
occuring.

-

[ message continues ]

I have written a sparse program to detect all callers that don't use
single-line literal strings for the printk format (posted to sparse
mailing list yesterday). So in fact, what I was doing was just that,
hunting them down and cleaning it up.

It so happens that my other patch also introduce a buffered printk
that supports atomic line continuations and multiple uninterrupted
lines, though this requires of course that the callers use these
functions. Other benefits include writing directly to the ring-buffer,
saving a 1K temporary buffer. The printk patch(es) can be viewed at
http://folk.uio.no/vegardno/xprintf/

Vegard
-

[ message continues ]