From b6d2c4475d5abc05dd009575b90556bdd3c78ad0 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Niklas=20Hamb=C3=BCchen?= Date: Thu, 8 Aug 2019 22:02:27 +0200 Subject: [PATCH] malloc: Fix missing accounting of top chunk in malloc_info [BZ #24026] Fixes ` 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 . That result being wrong makes investigating memory fragmentation issues like close to impossible. --- ChangeLog | 6 ++++++ malloc/malloc.c | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/ChangeLog b/ChangeLog index 760698b440..d094614589 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2019-08-08 Niklas Hambüchen + Carlos O'Donell + + [BZ #24026] + * malloc/malloc.c (__malloc_info): Account for top chunk. + 2019-08-07 Joseph Myers * sysdeps/unix/sysv/linux/bits/fcntl-linux.h [__USE_GNU] diff --git a/malloc/malloc.c b/malloc/malloc.c index 343d89f489..0e65d636cd 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); -- 2.43.5