On Sun, 2013-01-06 at 08:48 +0000, Liu Hui-R64343 wrote: > >-----Original Message----- > >From: Wanpeng Li [mailto:liwanp@xxxxxxxxxxxxxxxxxx] > >Sent: Sunday, January 06, 2013 4:46 PM > >To: Liu Hui-R64343 > >Cc: linux-kernel@xxxxxxxxxxxxxxx; mgorman@xxxxxxx; akpm@linux- > >foundation.org; riel@xxxxxxxxxx; minchan@xxxxxxxxxx; > >kamezawa.hiroyu@xxxxxxxxxxxxxx; linux-mm@xxxxxxxxx > >Subject: Re: [PATCH] mm: compaction: fix echo 1 > compact_memory return > >error issue > > > >On Sun, Jan 06, 2013 at 08:11:58AM +0000, Liu Hui-R64343 wrote: > >>>-----Original Message----- > >>>From: Wanpeng Li [mailto:liwanp@xxxxxxxxxxxxxxxxxx] > >>>Sent: Sunday, January 06, 2013 4:00 PM > >>>To: Liu Hui-R64343 > >>>Cc: linux-kernel@xxxxxxxxxxxxxxx; mgorman@xxxxxxx; akpm@linux- > >>>foundation.org; riel@xxxxxxxxxx; minchan@xxxxxxxxxx; > >>>kamezawa.hiroyu@xxxxxxxxxxxxxx; linux-mm@xxxxxxxxx > >>>Subject: Re: [PATCH] mm: compaction: fix echo 1 > compact_memory > >>>return error issue > >>> > >>>On Sun, Jan 06, 2013 at 03:44:33PM +0800, Jason Liu wrote: > >>> > >>>Hi Jason, > >>> > >>>>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 > >>>> > >>> > >>>How can you modify the value through none privileged user since the > >>>mode == 0200? > >> > >>I write it through privileged user(root). I'm using the GNOME_Mobile rootfs. > >> > >>> > >>>>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. > >>> > >>>What's the special scenario you are in? I couldn't figure out the > >>>similar error against latest 3.8-rc2, how could you reproduce it? > >> > >>I'm using the BusyBox v1.20.2 () built-in shell (ash), it reproduces the issue: > >100%. > >> > >>root@freescale /$ sh > >> > >> > >>BusyBox v1.20.2 () built-in shell (ash) Enter 'help' for a list of > >>built-in commands. > >> > >>Could you run strace and see the log: strace echo 1 > > >>/proc/sys/vm/compact_memory > >> > > > >I test it on my desktop against latest 3.8-rc2, can't repoduce it. :) > > > >write(1, "1\n", 2) = 3 > > Here it tells it. Why this value trouble you? > > >close(1) = 0 > >munmap(0xb779c000, 4096) = 0 > >close(2) = 0 > >exit_group(0) = ? > >+++ exited with 0 +++ > > > >Regards, > >Wanpeng Li > > > >>> > >>>Regards, > >>>Wanpeng Li > >>> > >>>> > >>>>Suggested-by:David Rientjes <rientjes@xxxxxxxxxx> Cc:Mel Gorman > >>>><mgorman@xxxxxxx> Cc:Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > >>>Cc:Rik > >>>>van Riel <riel@xxxxxxxxxx> Cc:Minchan Kim <minchan@xxxxxxxxxx> > >>>>Cc:KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > >>>>Signed-off-by: Jason Liu <r64343@xxxxxxxxxxxxx> > >>>>--- > >>>> mm/compaction.c | 6 ++---- > >>>> 1 files changed, 2 insertions(+), 4 deletions(-) > >>>> > >>>>diff --git a/mm/compaction.c b/mm/compaction.c index 6b807e4..f8f5c11 > >>>>100644 > >>>>--- a/mm/compaction.c > >>>>+++ b/mm/compaction.c > >>>>@@ -1210,7 +1210,7 @@ static int compact_node(int nid) } > >>>> > >>>> /* Compact all nodes in the system */ -static int > >>>>compact_nodes(void) > >>>>+static void compact_nodes(void) > >>>> { > >>>> int nid; > >>>> > >>>>@@ -1219,8 +1219,6 @@ static int compact_nodes(void) > >>>> > >>>> for_each_online_node(nid) > >>>> compact_node(nid); > >>>>- > >>>>- return COMPACT_COMPLETE; > >>>> } > >>>> > >>>> /* The written value is actually unused, all memory is compacted */ > >>>>@@ > >>>>-1231,7 +1229,7 @@ int sysctl_compaction_handler(struct ctl_table > >>>>*table, > >>>int write, > >>>> void __user *buffer, size_t *length, loff_t *ppos) { > >>>> if (write) > >>>>- return compact_nodes(); > >>>>+ compact_nodes(); > >>>> > >>>> return 0; > >>>> } > >>>>-- > >>>>1.7.5.4 > >>>> > >>>> > >>>>-- > >>>>To unsubscribe, send a message with 'unsubscribe linux-mm' in the > >>>>body to majordomo@xxxxxxxxx. For more info on Linux MM, > >>>>see: http://www.linux-mm.org/ . > >>>>Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > >>> > >> > > > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>