Using madvise with MADV_DONTNEED to release memory back to the kernel
is not sufficient to change the commit charge accounted against the
process on Linux. It is OK however, when overcommit is enabled or is
heuristic. However, when overcommit is restricted to a percentage of
memory setting the contents of /proc/sys/vm/overcommit_memory as 2, it
makes a difference since memory requests will fail. Hence, we do what
we do with secure exec binaries, which is to call mmap on the region
to be dropped with MAP_FIXED. This internally unmaps the pages in
question and reduces the amount of memory accounted against the
process.
[BZ #1349]
malloc_usable_size returns the usable size in an allocated chunk,
which may be >= the requested size. In the case of MALLOC_CHECK_ being
exported to > 0 however, only the requested size is usable, since a
magic value is written at the end of the request size to trap writes
beyond request bounds. Hence, when MALLOC_CHECK_ is exported to > 0,
malloc_usable_size() should return the request size.
* malloc.c/arena.c (reused_arena): New parameter, avoid_arena.
When avoid_arena is set, don't retry in the that arena. Pick the
next one, whatever it might be.
(arena_get2): New parameter avoid_arena, pass through to reused_arena.
(arena_lock): Pass in new parameter to arena_get2.
* malloc/malloc.c (__libc_memalign): Pass in new parameter to
arena_get2.
(__libc_malloc): Unify retrying after main arena failure with
__libc_memalign version.
(__libc_valloc, __libc_pvalloc, __libc_calloc): Likewise.
tst-obprintf failed with GCC 4.7.
It turned out that this is the fault of GCC optimizing away the
following from malloc/mcheck.c:
/* We call malloc() once here to ensure it is initialized. */
void *p = malloc (0);
free (p);
gcc sees the malloc(0);free pair and removes it completely.
And now malloc is not properly initialized and we screw up if both
mcheck is used (via tst-obprintf) and MALLOC_CHECK_ is set (as it is in my
environment).
obstack calls several callbacks, so on i?86 it'd better be compiled
without -mpreferred-stack-boundary=2, otherwise the callbacks are called
with misaligned stack.
With atomic fastbins the checks performed can race with concurrent
modifications of the arena. If we detect a problem re-do the test
after getting the lock.
The following patch fixes catomic_compare_and_exchange_*_rel definitions
(which were never used and weren't correct) and uses
catomic_compare_and_exchange_val_rel in _int_free. Comparing to the
pre-2009-07-02 --enable-experimental-malloc state the generated code should
be identical on all arches other than ppc/ppc64 and on ppc/ppc64 should use
lwsync instead of isync barrier.
2009-04-16 Ulrich Drepper <drepper@redhat.com>
[BZ #9957]
* malloc/malloc.c (force_reg): Define.
(sYSMALLOc): Load hook variable into variable
before test and force into register.
(sYSTRIm): Likewise.
(public_mALLOc): Force hook value into register.
(public_fREe): Likewise.
(public_rEALLOc): Likewise.
(public_mEMALIGn): Likewise.
(public_vALLOc): Likewise.
(public_pVALLOc): Likewise.
(public_cALLOc): Likewise.
(__posix_memalign): Likewise.
* malloc/arena.c (ptmalloc_init): Load hook variable into variable
before test and force into register.
* malloc/hooks.c (top_check): Likewise.
(public_s_ET_STATe): Pretty printing.
* resolv/res_send.c (send_dg): Don't just ignore the result we got
in case we only receive one reply in single-request mode.
Change all callers.
(_int_realloc): Likewise.
All _int_* functions are now static.
* malloc/hooks.c: Change all callers to _int_free and _int_realloc.
* malloc/arena.c: Likewise.
* include/malloc.h: Remove now unnecessary declarations of the _int_*
functions.
* elf/ldd.bash.in: Likewise.
* elf/sprof.c: Likewise.
* locale/programs/locale.c: Likewise.
* malloc/memusage.sh: Likewise.
* nss/getent.c: Likewise.
2009-02-06 Joseph Myers <joseph@codesourcery.com>
* debug/pcprofiledump.c (print_version,
argp_program_version_hook): New function.
* elf/ldconfig.c (more_help): New function.
(argp): Use it.
* elf/sln.c (usage): New function.
(main): Support --help and --version.
* malloc/memusagestat.c (print_version): New function.
(argp_program_version_hook): New variable.
* nscd/nscd.c (more_help): New function.
(argp): Use it.
* posix/getconf.c (main): Send --version output to stdout.
Support --help.
* sunrpc/rpc_main.c (usage, options_usage): Take STREAM and STATUS
arguments. All callers changed.
(print_version): New function.
(parseargs): Support --help and --version.
* sunrpc/rpcinfo.c (usage): Take STREAM argument. All callers
changed.
(print_version): New function.
(main): Use getopt_long. Support --help and --version.
* sysdeps/unix/sysv/linux/lddlibc4.c (main): Support --help and
--version.
2009-02-06 Ulrich Drepper <drepper@redhat.com>