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authorOleg Nesterov <oleg@redhat.com>2013-10-16 22:10:04 +0200
committerIngo Molnar <mingo@kernel.org>2013-10-29 12:02:52 +0100
commit3ea2f2b96f9e636f49eb10962e96db3e19cab157 (patch)
tree47cbcc90d4daa2155c2a5f0ebd357a0499d78316 /kernel/events
parent32c5fb7e7d18b4fd37c5e29dea731151e9d66866 (diff)
downloadop-kernel-dev-3ea2f2b96f9e636f49eb10962e96db3e19cab157.zip
op-kernel-dev-3ea2f2b96f9e636f49eb10962e96db3e19cab157.tar.gz
perf: Do not waste PAGE_SIZE bytes for ALIGN(8) in perf_event_mmap_event()
perf_event_mmap_event() does kzalloc(PATH_MAX + sizeof(u64)) to ensure we can align the size later. However this means that we actually allocate PAGE_SIZE * 2 buffer, seems too much. Change this code to allocate PATH_MAX==PAGE_SIZE bytes, but tell d_path() to not use the last sizeof(u64) bytes. Note: it is not clear why do we need __GFP_ZERO, see the next patch. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20131016201004.GC23214@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3ea5605..b409e75 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5113,17 +5113,18 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
if (file) {
struct inode *inode;
dev_t dev;
- /*
- * d_path works from the end of the rb backwards, so we
- * need to add enough zero bytes after the string to handle
- * the 64bit alignment we do later.
- */
- buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL);
+
+ buf = kzalloc(PATH_MAX, GFP_KERNEL);
if (!buf) {
name = strncpy(tmp, "//enomem", sizeof(tmp));
goto got_name;
}
- name = d_path(&file->f_path, buf, PATH_MAX);
+ /*
+ * d_path() works from the end of the rb backwards, so we
+ * need to add enough zero bytes after the string to handle
+ * the 64bit alignment we do later.
+ */
+ name = d_path(&file->f_path, buf, PATH_MAX - sizeof(u64));
if (IS_ERR(name)) {
name = strncpy(tmp, "//toolong", sizeof(tmp));
goto got_name;
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