>-----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. >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