It is enabled as default for glibc.malloc.hugetlb set to 2 or higher.
It also uses a non configurable minimum value and maximum value,
currently set respectively to 1 and 4 selected huge page size.
The arena allocation with huge pages does not use MAP_NORESERVE. As
indicate by kernel internal documentation [1], the flag might trigger
a SIGBUS on soft page faults if at memory access there is no left
pages in the pool.
On systems without a reserved huge pages pool, is just stress the
mmap(MAP_HUGETLB) allocation failure. To improve test coverage it is
required to create a pool with some allocated pages.
Checked on x86_64-linux-gnu with no reserved pages, 10 reserved pages
(which trigger mmap(MAP_HUGETBL) failures) and with 256 reserved pages
(which does not trigger mmap(MAP_HUGETLB) failures).
[1] https://www.kernel.org/doc/html/v4.18/vm/hugetlbfs_reserv.html#resv-map-modifications
Reviewed-by: DJ Delorie <dj@redhat.com>
With the morecore hook removed, there is not easy way to provide huge
pages support on with glibc allocator without resorting to transparent
huge pages. And some users and programs do prefer to use the huge pages
directly instead of THP for multiple reasons: no splitting, re-merging
by the VM, no TLB shootdowns for running processes, fast allocation
from the reserve pool, no competition with the rest of the processes
unlike THP, no swapping all, etc.
This patch extends the 'glibc.malloc.hugetlb' tunable: the value
'2' means to use huge pages directly with the system default size,
while a positive value means and specific page size that is matched
against the supported ones by the system.
Currently only memory allocated on sysmalloc() is handled, the arenas
still uses the default system page size.
To test is a new rule is added tests-malloc-hugetlb2, which run the
addes tests with the required GLIBC_TUNABLE setting. On systems without
a reserved huge pages pool, is just stress the mmap(MAP_HUGETLB)
allocation failure. To improve test coverage it is required to create
a pool with some allocated pages.
Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
Linux Transparent Huge Pages (THP) current supports three different
states: 'never', 'madvise', and 'always'. The 'never' is
self-explanatory and 'always' will enable THP for all anonymous
pages. However, 'madvise' is still the default for some system and
for such case THP will be only used if the memory range is explicity
advertise by the program through a madvise(MADV_HUGEPAGE) call.
To enable it a new tunable is provided, 'glibc.malloc.hugetlb',
where setting to a value diffent than 0 enables the madvise call.
This patch issues the madvise(MADV_HUGEPAGE) call after a successful
mmap() call at sysmalloc() with sizes larger than the default huge
page size. The madvise() call is disable is system does not support
THP or if it has the mode set to "never" and on Linux only support
one page size for THP, even if the architecture supports multiple
sizes.
To test is a new rule is added tests-malloc-hugetlb1, which run the
addes tests with the required GLIBC_TUNABLE setting.
Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
mcheck and malloc-check no longer work with static binaries, so drop
those tests.
Reported-by: Samuel Thibault <samuel.thibault@gnu.org>
Tested-by: Samuel Thibault <samuel.thibault@gnu.org>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Interpose malloc_usable_size to return the correct mcheck value for
malloc_usable_size.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
These deprecated functions are only safe to call from
__malloc_initialize_hook and as a result, are not useful in the
general case. Move the implementations to libc_malloc_debug so that
existing binaries that need it will now have to preload the debug DSO
to work correctly.
This also allows simplification of the core malloc implementation by
dropping all the undumping support code that was added to make
malloc_set_state work.
One known breakage is that of ancient emacs binaries that depend on
this. They will now crash when running with this libc. With
LD_BIND_NOW=1, it will terminate immediately because of not being able
to find malloc_set_state but with lazy binding it will crash in
unpredictable ways. It will need a preloaded libc_malloc_debug.so so
that its initialization hook is executed to allow its malloc
implementation to work properly.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The malloc-check debugging feature is tightly integrated into glibc
malloc, so thanks to an idea from Florian Weimer, much of the malloc
implementation has been moved into libc_malloc_debug.so to support
malloc-check. Due to this, glibc malloc and malloc-check can no
longer work together; they use altogether different (but identical)
structures for heap management. This should not make a difference
though since the malloc check hook is not disabled anywhere.
malloc_set_state does, but it does so early enough that it shouldn't
cause any problems.
The malloc check tunable is now in the debug DSO and has no effect
when the DSO is not preloaded.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Split the mcheck implementation into the debugging hooks and API so
that the API can be replicated in libc and libc_malloc_debug.so. The
libc APIs always result in failure.
The mcheck implementation has also been moved entirely into
libc_malloc_debug.so and with it, all of the hook initialization code
can now be moved into the debug library. Now the initialization can
be done independently of libc internals.
With this patch, libc_malloc_debug.so can no longer be used with older
libcs, which is not its goal anyway. tst-vfork3 breaks due to this
since it spawns shell scripts, which in turn execute using the system
glibc. Move the test to tests-container so that only the built glibc
is used.
This move also fixes bugs in the mcheck version of memalign and
realloc, thus allowing removal of the tests from tests-mcheck
exclusion list.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Remove all malloc hook uses from core malloc functions and move it
into a new library libc_malloc_debug.so. With this, the hooks now no
longer have any effect on the core library.
libc_malloc_debug.so is a malloc interposer that needs to be preloaded
to get hooks functionality back so that the debugging features that
depend on the hooks, i.e. malloc-check, mcheck and mtrace work again.
Without the preloaded DSO these debugging features will be nops.
These features will be ported away from hooks in subsequent patches.
Similarly, legacy applications that need hooks functionality need to
preload libc_malloc_debug.so.
The symbols exported by libc_malloc_debug.so are maintained at exactly
the same version as libc.so.
Finally, static binaries will no longer be able to use malloc
debugging features since they cannot preload the debugging DSO.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Make the __morecore and __default_morecore symbols compat-only and
remove their declarations from the API. Also, include morecore.c
directly into malloc.c; this should ideally get merged into malloc in
a future cleanup.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Targets with base versions of 2.24 or later won't have
__malloc_initialize_hook because of which the tests will essentially
be the same as the regular malloc tests. Avoid running them instead
and save time.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
1. Align struct hdr to MALLOC_ALIGNMENT bytes so that malloc hooks in
libmcheck align memory to MALLOC_ALIGNMENT bytes.
2. Remove tst-mallocalign1 from tests-exclude-mcheck for i386 and x32.
3. Add tst-pvalloc-fortify and tst-reallocarray to tests-exclude-mcheck
since they use malloc_usable_size (see BZ #22057).
This fixed BZ #28068.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
1. Add sysdeps/generic/malloc-size.h to define size related macros for
malloc.
2. Move x86_64/tst-mallocalign1.c to malloc and replace ALIGN_MASK with
MALLOC_ALIGN_MASK.
3. Add tst-mallocalign1 to tests-exclude-mcheck for i386 and x32 since
mcheck doesn't honor MALLOC_ALIGNMENT.
It's tst-realloc, not tst-posix-realloc. Verified this time to ensure
that the total number of tests reduced by 1.
Reported-by: Stefan Liebler <stli@linux.ibm.com>
The realloc (NULL, 0) test in tst-realloc fails with gcc 7.x but
passes with newer gcc. This is because a newer gcc transforms the
realloc call to malloc (0), thus masking the bug in mcheck.
Disable the test with mcheck for now. The malloc removal patchset
will fix this and then remove this test from the exclusion list.
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Dependencies on hooks.c and arena.c get auto-computed when generating
malloc.o{,s}.d so there is no need to add them manually.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>
Like malloc-check, add generic rules to run all tests in malloc by
linking with libmcheck.a so as to provide coverage for mcheck().
Currently the following 12 tests fail:
FAIL: malloc/tst-malloc-backtrace-mcheck
FAIL: malloc/tst-malloc-fork-deadlock-mcheck
FAIL: malloc/tst-malloc-stats-cancellation-mcheck
FAIL: malloc/tst-malloc-tcache-leak-mcheck
FAIL: malloc/tst-malloc-thread-exit-mcheck
FAIL: malloc/tst-malloc-thread-fail-mcheck
FAIL: malloc/tst-malloc-usable-static-mcheck
FAIL: malloc/tst-malloc-usable-static-tunables-mcheck
FAIL: malloc/tst-malloc-usable-tunables-mcheck
FAIL: malloc/tst-malloc_info-mcheck
FAIL: malloc/tst-memalign-mcheck
FAIL: malloc/tst-posix_memalign-mcheck
and they have been added to tests-exclude-mcheck for now to keep
status quo. At least the last two can be attributed to bugs in
mcheck() but I haven't fixed them here since they should be fixed by
removing malloc hooks. Others need to be triaged to check if they're
due to mcheck bugs or due to actual bugs.
Reviewed-by: DJ Delorie <dj@redhat.com>
Austin Group issue 62 [1] dropped the async-signal-safe requirement
for fork and provided a async-signal-safe _Fork replacement that
does not run the atfork handlers. It will be included in the next
POSIX standard.
It allow to close a long standing issue to make fork AS-safe (BZ#4737).
As indicated on the bug, besides the internal lock for the atfork
handlers itself; there is no guarantee that the handlers itself will
not introduce more AS-safe issues.
The idea is synchronize fork with the required internal locks to allow
children in multithread processes to use mostly of standard function
(even though POSIX states only AS-safe function should be used). On
signal handles, _Fork should be used intead and only AS-safe functions
should be used.
For testing, the new tst-_Fork only check basic usage. I also added
a new tst-mallocfork3 which uses the same strategy to check for
deadlock of tst-mallocfork2 but using threads instead of subprocesses
(and it does deadlock if it replaces _Fork with fork).
[1] https://austingroupbugs.net/view.php?id=62
MALLOC_CHECK_ and mcheck() are two different malloc checking features.
tst-mcheck does not check mcheck(), instead it checks MALLOC_CHECK_,
so rename the file to avoid confusion.
This commit removes the ELF constructor and internal variables from
dlfcn/dlfcn.c. The file now serves the same purpose as
nptl/libpthread-compat.c, so it is renamed to dlfcn/libdl-compat.c.
The use of libdl-shared-only-routines ensures that libdl.a is empty.
This commit adjusts the test suite not to use $(libdl). The libdl.so
symbolic link is no longer installed.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When MALLOC_CHECK_ is non-zero, the realloc hook missed to set errno to
ENOMEM when called with too big size. Run the test tst-malloc-too-large
also with MALLOC_CHECK_=3 to catch that.
(FYI, this is a repost of
https://sourceware.org/pipermail/libc-alpha/2019-July/105035.html now
that FSF papers have been signed and confirmed on FSF side).
This trivial patch attemps to fix BZ 24106. Basically the bash locally
used when building glibc on the host shall not leak on the installed
glibc, as the system where it is installed might be different and use
another bash location.
So I have looked for all occurences of @BASH@ or $(BASH) in installed
files, and replaced it by /bin/bash. This was suggested by Florian
Weimer in the bug report.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
compat_symbol_reference no longer needs tests-internal. Do not build
the test at all for newer targets, so that no spurious UNSUPPORTED
result is generated. Use compat_symbol_reference for
__malloc_initialize_hook as well, eliminating the need for -rdynamic.
Reviewed-by: DJ Delorie <dj@redhat.com>
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
In the next release of POSIX, free must preserve errno
<https://www.austingroupbugs.net/view.php?id=385>.
Modify __libc_free to save and restore errno, so that
any internal munmap etc. syscalls do not disturb the caller's errno.
Add a test malloc/tst-free-errno.c (almost all by Bruno Haible),
and document that free preserves errno.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This new variable allows various subsystems in glibc to run all or
some of their tests with MALLOC_CHECK_=3. This patch adds
infrastructure support for this variable as well as an implementation
in malloc/Makefile to allow running some of the tests with
MALLOC_CHECK_=3.
At present some tests in malloc/ have been excluded from the mcheck
tests either because they're specifically testing MALLOC_CHECK_ or
they are failing in master even without the Memory Tagging patches
that prompted this work. Some tests were reviewed and found to need
specific error points that MALLOC_CHECK_ defeats by terminating early
but a thorough review of all tests is needed to bring them into mcheck
coverage.
The following failures are seen in current master:
FAIL: malloc/tst-malloc-fork-deadlock-mcheck
FAIL: malloc/tst-malloc-stats-cancellation-mcheck
FAIL: malloc/tst-malloc-thread-fail-mcheck
FAIL: malloc/tst-realloc-mcheck
FAIL: malloc/tst-reallocarray-mcheck
All of these are due to the Memory Tagging patchset and will be fixed
separately.
This patch adds the ABI-related bits to reflect the new mallinfo2
function, and adds a test case to verify basic functionality.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Adding the test "tst-safe-linking" for testing that Safe-Linking works
as expected. The test checks these 3 main flows:
* tcache protection
* fastbin protection
* malloc_consolidate() correctness
As there is a random chance of 1/16 that of the alignment will remain
correct, the test checks each flow up to 10 times, using different random
values for the pointer corruption. As a result, the chance for a false
failure of a given tested flow is 2**(-40), thus highly unlikely.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
pvalloc is guarantueed to round up the allocation size to the page
size, so applications can assume that the memory region is larger
than the passed-in argument. The alloc_size attribute cannot express
that.
The test case is based on a suggestion from Jakub Jelinek.
This fixes commit 9bf8e29ca1 ("malloc:
make malloc fail with requests larger than PTRDIFF_MAX (BZ#23741)").
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This synchronization method has a lower overhead and makes
it more likely that the signal arrives during one of the critical
functions.
Also test for fork deadlocks explicitly.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
The memusagestat is the only binary that has its own link line which
causes it to be linked against the existing installed C library. It
has been this way since it was originally committed in 1999, but I
don't see any reason as to why. Since we want all the programs we
build locally to be against the new copy of glibc, change the build
to be like all other programs.
This one tests for BZ#23907 where the double free
test didn't check the tcache bin bounds before dereferencing
the bin.
[BZ #23907]
* malloc/tst-tcfree3.c: New.
* malloc/Makefile: Add it.
malloc_stats means to disable cancellation for writes to stderr while
it runs, but it restores stderr->_flags2 with |= instead of =, so what
it actually does is disable cancellation on stderr permanently.
[BZ #22830]
* malloc/malloc.c (__malloc_stats): Restore stderr->_flags2
correctly.
* malloc/tst-malloc-stats-cancellation.c: New test case.
* malloc/Makefile: Add new test case.
When posix_memalign is called with an alignment less than MALLOC_ALIGNMENT
and a requested size close to SIZE_MAX, it falls back to malloc code
(because the alignment of a block returned by malloc is sufficient to
satisfy the call). In this case, an integer overflow in _int_malloc leads
to posix_memalign incorrectly returning successfully.
Upon fixing this and writing a somewhat thorough regression test, it was
discovered that when posix_memalign is called with an alignment larger than
MALLOC_ALIGNMENT (so it uses _int_memalign instead) and a requested size
close to SIZE_MAX, a different integer overflow in _int_memalign leads to
posix_memalign incorrectly returning successfully.
Both integer overflows affect other memory allocation functions that use
_int_malloc (one affected malloc in x86) or _int_memalign as well.
This commit fixes both integer overflows. In addition to this, it adds a
regression test to guard against false successful allocations by the
following memory allocation functions when called with too-large allocation
sizes and, where relevant, various valid alignments:
malloc, realloc, calloc, reallocarray, memalign, posix_memalign,
aligned_alloc, valloc, and pvalloc.
The malloc tcache added in 2.26 will leak all of the elements remaining
in the cache and the cache structure itself when a thread exits. The
defect is that we do not set tcache_shutting_down early enough, and the
thread simply recreates the tcache and places the elements back onto a
new tcache which is subsequently lost as the thread exits (unfreed
memory). The fix is relatively simple, move the setting of
tcache_shutting_down earlier in tcache_thread_freeres. We add a test
case which uses mallinfo and some heuristics to look for unaccounted for
memory usage between the start and end of a thread start/join loop. It
is very reliable at detecting that there is a leak given the number of
iterations. Without the fix the test will consume 122MiB of leaked
memory.
