Bug#695182: [PATCH] Subtract min_free_kbytes from dirtyable memory
On Mon, 21 Jan 2013 14:15:49 +1100
paul.szabo@sydney.edu.au wrote:
> When calculating amount of dirtyable memory, min_free_kbytes should be
> subtracted because it is not intended for dirty pages.
Makes sense.
> Using an "extern int" because that is the only interface to some such
> sysctl values.
urgh, not that way. Let's do it properly:
From: Andrew Morton <akpm@linux-foundation.org>
Subject: page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix
fix up min_free_kbytes extern declarations
Cc: Paul Szabo <psz@maths.usyd.edu.au>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 3 +++
kernel/sysctl.c | 1 -
mm/huge_memory.c | 1 -
mm/page-writeback.c | 1 -
4 files changed, 3 insertions(+), 3 deletions(-)
--- a/mm/page-writeback.c~page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix
+++ a/mm/page-writeback.c
@@ -233,7 +233,6 @@ static unsigned long highmem_dirtyable_m
static unsigned long global_dirtyable_memory(void)
{
unsigned long x;
- extern int min_free_kbytes;
x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
x -= min(x, dirty_balance_reserve);
--- a/include/linux/mm.h~page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix
+++ a/include/linux/mm.h
@@ -1387,6 +1387,9 @@ extern void setup_per_cpu_pageset(void);
extern void zone_pcp_update(struct zone *zone);
extern void zone_pcp_reset(struct zone *zone);
+/* page_alloc.c */
+extern int min_free_kbytes;
+
/* nommu.c */
extern atomic_long_t mmap_pages_allocated;
extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
--- a/mm/huge_memory.c~page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix
+++ a/mm/huge_memory.c
@@ -105,7 +105,6 @@ static int set_recommended_min_free_kbyt
struct zone *zone;
int nr_zones = 0;
unsigned long recommended_min;
- extern int min_free_kbytes;
if (!khugepaged_enabled())
return 0;
--- a/kernel/sysctl.c~page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix
+++ a/kernel/sysctl.c
@@ -104,7 +104,6 @@ extern char core_pattern[];
extern unsigned int core_pipe_limit;
#endif
extern int pid_max;
-extern int min_free_kbytes;
extern int pid_max_min, pid_max_max;
extern int sysctl_drop_caches;
extern int percpu_pagelist_fraction;
_
> (This patch does not solve the PAE OOM issue.)
>
> Paul Szabo psz@maths.usyd.edu.au http://www.maths.usyd.edu.au/u/psz/
> School of Mathematics and Statistics University of Sydney Australia
>
> Reported-by: Paul Szabo <psz@maths.usyd.edu.au>
Reported-by isn't needed in such cases. It is assumed that finder==fixer.
> Reference: http://bugs.debian.org/695182
> Signed-off-by: Paul Szabo <psz@maths.usyd.edu.au>
>
> --- mm/page-writeback.c.old 2012-12-06 22:20:40.000000000 +1100
> +++ mm/page-writeback.c 2013-01-21 13:57:05.000000000 +1100
Please prepare patches in `patch -p1' form. This should be covered in
Documentation/SubmittingPatches, but isn't.
Documentation/applying-patches.txt mentions it.
> @@ -343,12 +343,16 @@
> unsigned long determine_dirtyable_memory(void)
You appear to be patching an old kernel. But the change is still
applicable, to global_dirtyable_memory().
> {
> unsigned long x;
> + extern int min_free_kbytes;
>
> x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
>
> if (!vm_highmem_is_dirtyable)
> x -= highmem_dirtyable_memory(x);
>
> + /* Subtract min_free_kbytes */
> + x -= min(x, min_free_kbytes >> (PAGE_SHIFT - 10));
Generates
mm/page-writeback.c:244: warning: comparison of distinct pointer types lacks a cast
because of the problematic min(int, unsigned long). min_free_kbytes
should have an unsigned (long?) type, but I can't be bothered fixing
that right now..
From: Andrew Morton <akpm@linux-foundation.org>
Subject: page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix-fix
fix min() warning
Cc: Paul Szabo <psz@maths.usyd.edu.au>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/page-writeback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/page-writeback.c~page-writebackc-subtract-min_free_kbytes-from-dirtyable-memory-fix-fix
+++ a/mm/page-writeback.c
@@ -241,7 +241,7 @@ static unsigned long global_dirtyable_me
x -= highmem_dirtyable_memory(x);
/* Subtract min_free_kbytes */
- x -= min(x, min_free_kbytes >> (PAGE_SHIFT - 10));
+ x -= min_t(unsigned long, x, min_free_kbytes >> (PAGE_SHIFT - 10));
return x + 1; /* Ensure that we never return 0 */
}
_
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