Merge git://git.infradead.org/battery-2.6

[safe/jmp/linux-2.6] / Documentation / sysctl / vm.txt

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index faf6274..6c7d18c 100644 (file)
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -370,7 +370,7 @@ The default is 1 percent.
 mmap_min_addr
 
 This file indicates the amount of address space  which a user process will
-be restricted from mmaping.  Since kernel null dereference bugs could
+be restricted from mmapping.  Since kernel null dereference bugs could
 accidentally operate based on the information in the first couple of pages
 of memory userspace processes should not be allowed to write to them.  By
 default this value is set to 0 and no protections will be enforced by the
@@ -573,11 +573,14 @@ Because other nodes' memory may be free. This means system total status
 may be not fatal yet.
 
 If this is set to 2, the kernel panics compulsorily even on the
-above-mentioned.
+above-mentioned. Even oom happens under memory cgroup, the whole
+system panics.
 
 The default value is 0.
 1 and 2 are for failover of clustering. Please select either
 according to your policy of failover.
+panic_on_oom=2+kdump gives you very strong tool to investigate
+why oom happens. You can get snapshot.
 
 =============================================================
 
@@ -624,7 +627,9 @@ caching of directory and inode objects.
 At the default value of vfs_cache_pressure=100 the kernel will attempt to
 reclaim dentries and inodes at a "fair" rate with respect to pagecache and
 swapcache reclaim.  Decreasing vfs_cache_pressure causes the kernel to prefer
-to retain dentry and inode caches.  Increasing vfs_cache_pressure beyond 100
+to retain dentry and inode caches. When vfs_cache_pressure=0, the kernel will
+never reclaim dentries and inodes due to memory pressure and this can easily
+lead to out-of-memory conditions. Increasing vfs_cache_pressure beyond 100
 causes the kernel to prefer to reclaim dentries and inodes.
 
 ==============================================================