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SubjectRe: [PATCH] mm: compaction: fix echo 1 > compact_memory return error issue
On Mon, 7 Jan 2013 13:57:21 +0000
Mel Gorman <mgorman@suse.de> wrote:

> On Sun, Jan 06, 2013 at 03:44:33PM +0800, Jason Liu wrote:
> > when run the folloing command under shell, it will return error
> > sh/$ echo 1 > /proc/sys/vm/compact_memory
> > sh/$ sh: write error: Bad address
> >
> > After strace, I found the following log:
> > ...
> > write(1, "1\n", 2) = 3
> > write(1, "", 4294967295) = -1 EFAULT (Bad address)
> > write(2, "echo: write error: Bad address\n", 31echo: write error: Bad address
> > ) = 31
> >
> > This tells system return 3(COMPACT_COMPLETE) after write data to compact_memory.
> >
> > The fix is to make the system just return 0 instead 3(COMPACT_COMPLETE) from
> > sysctl_compaction_handler after compaction_nodes finished.
> >
> > Suggested-by:David Rientjes <rientjes@google.com>
> > Cc:Mel Gorman <mgorman@suse.de>
> > Cc:Andrew Morton <akpm@linux-foundation.org>
> > Cc:Rik van Riel <riel@redhat.com>
> > Cc:Minchan Kim <minchan@kernel.org>
> > Cc:KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > Signed-off-by: Jason Liu <r64343@freescale.com>
>
> Acked-by: Mel Gorman <mgorman@suse.de>

We have a whole pile of things around there which return
information-free integers. Should we do this?

--- a/mm/compaction.c~mm-compaction-fix-echo-1-compact_memory-return-error-issue-fix
+++ a/mm/compaction.c
@@ -1150,7 +1150,7 @@ unsigned long try_to_compact_pages(struc


/* Compact all zones within a node */
-static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
+static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
{
int zoneid;
struct zone *zone;
@@ -1183,11 +1183,9 @@ static int __compact_pgdat(pg_data_t *pg
VM_BUG_ON(!list_empty(&cc->freepages));
VM_BUG_ON(!list_empty(&cc->migratepages));
}
-
- return 0;
}

-int compact_pgdat(pg_data_t *pgdat, int order)
+void compact_pgdat(pg_data_t *pgdat, int order)
{
struct compact_control cc = {
.order = order,
@@ -1195,10 +1193,10 @@ int compact_pgdat(pg_data_t *pgdat, int
.page = NULL,
};

- return __compact_pgdat(pgdat, &cc);
+ __compact_pgdat(pgdat, &cc);
}

-static int compact_node(int nid)
+static void compact_node(int nid)
{
struct compact_control cc = {
.order = -1,
@@ -1206,7 +1204,7 @@ static int compact_node(int nid)
.page = NULL,
};

- return __compact_pgdat(NODE_DATA(nid), &cc);
+ __compact_pgdat(NODE_DATA(nid), &cc);
}

/* Compact all nodes in the system */
diff -puN include/linux/compaction.h~mm-compaction-fix-echo-1-compact_memory-return-error-issue-fix include/linux/compaction.h
--- a/include/linux/compaction.h~mm-compaction-fix-echo-1-compact_memory-return-error-issue-fix
+++ a/include/linux/compaction.h
@@ -23,7 +23,7 @@ extern int fragmentation_index(struct zo
extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
int order, gfp_t gfp_mask, nodemask_t *mask,
bool sync, bool *contended, struct page **page);
-extern int compact_pgdat(pg_data_t *pgdat, int order);
+extern void compact_pgdat(pg_data_t *pgdat, int order);
extern void reset_isolation_suitable(pg_data_t *pgdat);
extern unsigned long compaction_suitable(struct zone *zone, int order);

@@ -80,9 +80,8 @@ static inline unsigned long try_to_compa
return COMPACT_CONTINUE;
}

-static inline int compact_pgdat(pg_data_t *pgdat, int order)
+static inline void compact_pgdat(pg_data_t *pgdat, int order)
{
- return COMPACT_CONTINUE;
}

static inline void reset_isolation_suitable(pg_data_t *pgdat)
_



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