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| author | David Rientjes <rientjes@google.com> | 2015-11-05 18:50:32 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-05 19:34:48 -0800 |
| commit | b72bdfa73603f2f81fbac651b9ae36807e877752 (patch) | |
| tree | d302a8fb0e69169ef9e0749918ab6f0fd26ac2a9 | |
| parent | c12176d3368b9b36ae484d323d41e94be26f9b65 (diff) | |
| download | linux-stable-b72bdfa73603f2f81fbac651b9ae36807e877752.tar.gz linux-stable-b72bdfa73603f2f81fbac651b9ae36807e877752.tar.bz2 linux-stable-b72bdfa73603f2f81fbac651b9ae36807e877752.zip | |
mm, oom: add comment for why oom_adj exists
/proc/pid/oom_adj exists solely to avoid breaking existing userspace
binaries that write to the tunable.
Add a comment in the only possible location within the kernel tree to
describe the situation and motivation for keeping it around.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/base.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 29595af32866..bd3e9e68125b 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1032,6 +1032,16 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count, return simple_read_from_buffer(buf, count, ppos, buffer, len); } +/* + * /proc/pid/oom_adj exists solely for backwards compatibility with previous + * kernels. The effective policy is defined by oom_score_adj, which has a + * different scale: oom_adj grew exponentially and oom_score_adj grows linearly. + * Values written to oom_adj are simply mapped linearly to oom_score_adj. + * Processes that become oom disabled via oom_adj will still be oom disabled + * with this implementation. + * + * oom_adj cannot be removed since existing userspace binaries use it. + */ static ssize_t oom_adj_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { |