This is the mail archive of the
glibc-cvs@sourceware.org
mailing list for the glibc project.
[glibc/release/2.30/master] malloc: Fix missing accounting of top chunk in malloc_info [BZ #24026]
- From: Arjun Shankar <arjun at sourceware dot org>
- To: glibc-cvs at sourceware dot org
- Date: 19 Nov 2019 12:12:14 -0000
- Subject: [glibc/release/2.30/master] malloc: Fix missing accounting of top chunk in malloc_info [BZ #24026]
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5f620768fbdae75f71af78852be228ad5577623d
commit 5f620768fbdae75f71af78852be228ad5577623d
Author: Niklas Hambüchen <mail@nh2.me>
Date: Thu Aug 8 22:02:27 2019 +0200
malloc: Fix missing accounting of top chunk in malloc_info [BZ #24026]
Fixes `<total type="rest" size="..."> incorrectly showing as 0 most
of the time.
The rest value being wrong is significant because to compute the
actual amount of memory handed out via malloc, the user must subtract
it from <system type="current" size="...">. That result being wrong
makes investigating memory fragmentation issues like
<https://bugzilla.redhat.com/show_bug.cgi?id=843478> close to
impossible.
(cherry picked from commit b6d2c4475d5abc05dd009575b90556bdd3c78ad0)
Diff:
---
ChangeLog | 6 ++++++
malloc/malloc.c | 6 ++++++
2 files changed, 12 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 43c9a70..e1d8fd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-08-08 Niklas Hambüchen <mail@nh2.me>
+ Carlos O'Donell <carlos@redhat.com>
+
+ [BZ #24026]
+ * malloc/malloc.c (__malloc_info): Account for top chunk.
+
2019-11-01 Dragan Mladjenovic <dmladjenovic@wavecomp.com>
* sysdeps/unix/sysv/linux/mips/Makefile
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 343d89f..0e65d63 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5406,6 +5406,12 @@ __malloc_info (int options, FILE *fp)
__libc_lock_lock (ar_ptr->mutex);
+ /* Account for top chunk. The top-most available chunk is
+ treated specially and is never in any bin. See "initial_top"
+ comments. */
+ avail = chunksize (ar_ptr->top);
+ nblocks = 1; /* Top always exists. */
+
for (size_t i = 0; i < NFASTBINS; ++i)
{
mchunkptr p = fastbin (ar_ptr, i);