diff mbox series

[v3] malloc: set NON_MAIN_ARENA flag for reclaimed memalign chunk (BZ #30101)

Message ID xnleixyckw.fsf@greed.delorie.com
State New
Headers show
Series [v3] malloc: set NON_MAIN_ARENA flag for reclaimed memalign chunk (BZ #30101) | expand

Commit Message

DJ Delorie April 12, 2023, 4 a.m. UTC
changes since v2:

* Use rounded-up size in chunk_ok_for_memalign() to make sure size
  checks pass later on.

From e7fca683c719cb6e1f9f4f47f76f1550c76d3c3c Mon Sep 17 00:00:00 2001
From: DJ Delorie <dj@redhat.com>
Date: Mon, 3 Apr 2023 17:33:03 -0400
Subject: malloc: set NON_MAIN_ARENA flag for reclaimed memalign chunk (BZ
 #30101)

Based on these comments in malloc.c:

   size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
   from a non-main arena.  This is only set immediately before handing
   the chunk to the user, if necessary.

   The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
   does not have to be taken into account in size comparisons.

When we pull a chunk off the unsorted list (or any list) we need to
make sure that flag is set properly before returning the chunk.

Also, use the rounded-up size for chunk_ok_for_memalign()

Comments

Cristian Rodríguez April 12, 2023, 1:11 p.m. UTC | #1
On Wed, Apr 12, 2023 at 12:00 AM DJ Delorie via Libc-alpha <
libc-alpha@sourceware.org> wrote:

>
> changes since v2:
>
> * Use rounded-up size in chunk_ok_for_memalign() to make sure size
>   checks pass later on.
>

Can this be committed so it gets exposed to a larger amount of apps ?
thanks.
DJ Delorie April 12, 2023, 4:46 p.m. UTC | #2
Cristian Rodrguez <crrodriguez@opensuse.org> writes:
> Can this be committed so it gets exposed to a larger amount of apps ?  
> thanks.

As per our usual procedures, it needs a consensus approval, which means
reviews done and Reviewed-by:'s given, etc.  If you wish to do a review
and give it a Reviewed-by: (or not ;), that would help build consensus.
diff mbox series

Patch

diff --git a/malloc/Makefile b/malloc/Makefile
index f49675845e..e66247ed01 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -43,7 +43,8 @@  tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
 	 tst-tcfree1 tst-tcfree2 tst-tcfree3 \
 	 tst-safe-linking \
 	 tst-mallocalign1 \
-	 tst-memalign-2
+	 tst-memalign-2 \
+	 tst-memalign-3
 
 tests-static := \
 	 tst-interpose-static-nothread \
@@ -71,7 +72,7 @@  test-srcs = tst-mtrace
 # with MALLOC_CHECK_=3 because they expect a specific failure.
 tests-exclude-malloc-check = tst-malloc-check tst-malloc-usable \
 	tst-mxfast tst-safe-linking \
-	tst-compathooks-off tst-compathooks-on tst-memalign-2
+	tst-compathooks-off tst-compathooks-on tst-memalign-2 tst-memalign-3
 
 # Run all tests with MALLOC_CHECK_=3
 tests-malloc-check = $(filter-out $(tests-exclude-malloc-check) \
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 0315ac5d16..8ed2ec553b 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5084,7 +5084,7 @@  _int_memalign (mstate av, size_t alignment, size_t bytes)
       fwd = bck->fd;
       while (fwd != bck)
 	{
-	  if (chunk_ok_for_memalign (fwd, alignment, bytes) > 0)
+	  if (chunk_ok_for_memalign (fwd, alignment, nb) > 0)
 	    {
 	      victim = fwd;
 
@@ -5114,7 +5114,7 @@  _int_memalign (mstate av, size_t alignment, size_t bytes)
 
 	  if (chunksize (fwd) < nb)
 	      break;
-	  extra = chunk_ok_for_memalign (fwd, alignment, bytes);
+	  extra = chunk_ok_for_memalign (fwd, alignment, nb);
 	  if (extra > 0
 	      && (extra <= best_size || best == NULL))
 	    {
@@ -5147,6 +5147,8 @@  _int_memalign (mstate av, size_t alignment, size_t bytes)
       p = victim;
       m = chunk2mem (p);
       set_inuse (p);
+      if (av != &main_arena)
+	set_non_main_arena (p);
     }
   else
     {
diff --git a/malloc/tst-memalign-2.c b/malloc/tst-memalign-2.c
index 4996578e9f..f229283dbf 100644
--- a/malloc/tst-memalign-2.c
+++ b/malloc/tst-memalign-2.c
@@ -33,9 +33,10 @@  typedef struct TestCase {
 } TestCase;
 
 static TestCase tcache_allocs[] = {
-  { 24, 8, NULL, NULL },
-  { 24, 16, NULL, NULL },
-  { 128, 32, NULL, NULL }
+  { 24, 32, NULL, NULL },
+  { 24, 64, NULL, NULL },
+  { 128, 128, NULL, NULL },
+  { 500, 128, NULL, NULL }
 };
 #define TN array_length (tcache_allocs)
 
@@ -70,11 +71,15 @@  do_test (void)
 
   for (i = 0; i < TN; ++ i)
     {
+      size_t sz2;
+
       tcache_allocs[i].ptr1 = memalign (tcache_allocs[i].alignment, tcache_allocs[i].size);
       CHECK (tcache_allocs[i].ptr1, tcache_allocs[i].alignment);
+      sz2 = malloc_usable_size (tcache_allocs[i].ptr1);
       free (tcache_allocs[i].ptr1);
+
       /* This should return the same chunk as was just free'd.  */
-      tcache_allocs[i].ptr2 = memalign (tcache_allocs[i].alignment, tcache_allocs[i].size);
+      tcache_allocs[i].ptr2 = memalign (tcache_allocs[i].alignment, sz2);
       CHECK (tcache_allocs[i].ptr2, tcache_allocs[i].alignment);
       free (tcache_allocs[i].ptr2);
 
diff --git a/malloc/tst-memalign-3.c b/malloc/tst-memalign-3.c
new file mode 100644
index 0000000000..ab90d6ca9b
--- /dev/null
+++ b/malloc/tst-memalign-3.c
@@ -0,0 +1,173 @@ 
+/* Test for memalign chunk reuse.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <malloc.h>
+#include <stdio.h>
+#include <pthread.h>
+#include <string.h>
+#include <unistd.h>
+#include <array_length.h>
+#include <libc-pointer-arith.h>
+#include <support/check.h>
+#include <support/xthread.h>
+
+
+typedef struct TestCase {
+  size_t size;
+  size_t alignment;
+  void *ptr1;
+  void *ptr2;
+} TestCase;
+
+static TestCase tcache_allocs[] = {
+  { 24, 32, NULL, NULL },
+  { 24, 64, NULL, NULL },
+  { 128, 128, NULL, NULL },
+  { 500, 128, NULL, NULL }
+};
+#define TN array_length (tcache_allocs)
+
+static TestCase large_allocs[] = {
+  { 23450, 64, NULL, NULL },
+  { 23450, 64, NULL, NULL },
+  { 23550, 64, NULL, NULL },
+  { 23550, 64, NULL, NULL },
+  { 23650, 64, NULL, NULL },
+  { 23650, 64, NULL, NULL },
+  { 33650, 64, NULL, NULL },
+  { 33650, 64, NULL, NULL }
+};
+#define LN array_length (large_allocs)
+
+void *p;
+
+/* Sanity checks, ancillary to the actual test.  */
+#define CHECK(p,a) \
+  if (p == NULL || !PTR_IS_ALIGNED (p, a)) \
+    FAIL_EXIT1 ("NULL or misaligned memory detected.\n");
+
+static void *
+mem_test (void *closure)
+{
+  int i;
+  int j;
+  int count;
+  void *ptr[10];
+  void *p;
+
+  /* TCache test.  */
+  for (i = 0; i < TN; ++ i)
+    {
+      size_t sz2;
+
+      tcache_allocs[i].ptr1 = memalign (tcache_allocs[i].alignment, tcache_allocs[i].size);
+      CHECK (tcache_allocs[i].ptr1, tcache_allocs[i].alignment);
+      sz2 = malloc_usable_size (tcache_allocs[i].ptr1);
+      free (tcache_allocs[i].ptr1);
+
+      /* This should return the same chunk as was just free'd.  */
+      tcache_allocs[i].ptr2 = memalign (tcache_allocs[i].alignment, sz2);
+      CHECK (tcache_allocs[i].ptr2, tcache_allocs[i].alignment);
+      free (tcache_allocs[i].ptr2);
+
+      TEST_VERIFY (tcache_allocs[i].ptr1 == tcache_allocs[i].ptr2);
+    }
+
+  /* Test for non-head tcache hits.  */
+  for (i = 0; i < array_length (ptr); ++ i)
+    {
+      if (i == 4)
+	{
+	  ptr[i] = memalign (64, 256);
+	  CHECK (ptr[i], 64);
+	}
+      else
+	{
+	  ptr[i] = malloc (256);
+	  CHECK (ptr[i], 4);
+	}
+    }
+  for (i = 0; i < array_length (ptr); ++ i)
+    free (ptr[i]);
+
+  p = memalign (64, 256);
+  CHECK (p, 64);
+
+  count = 0;
+  for (i = 0; i < 10; ++ i)
+    if (ptr[i] == p)
+      ++ count;
+  free (p);
+  TEST_VERIFY (count > 0);
+
+  /* Large bins test.  */
+
+  for (i = 0; i < LN; ++ i)
+    {
+      large_allocs[i].ptr1 = memalign (large_allocs[i].alignment, large_allocs[i].size);
+      CHECK (large_allocs[i].ptr1, large_allocs[i].alignment);
+      /* Keep chunks from combining by fragmenting the heap.  */
+      p = malloc (512);
+      CHECK (p, 4);
+    }
+
+  for (i = 0; i < LN; ++ i)
+    free (large_allocs[i].ptr1);
+
+  /* Force the unsorted bins to be scanned and moved to small/large
+     bins.  */
+  p = malloc (60000);
+
+  for (i = 0; i < LN; ++ i)
+    {
+      large_allocs[i].ptr2 = memalign (large_allocs[i].alignment, large_allocs[i].size);
+      CHECK (large_allocs[i].ptr2, large_allocs[i].alignment);
+    }
+
+  count = 0;
+  for (i = 0; i < LN; ++ i)
+    {
+      int ok = 0;
+      for (j = 0; j < LN; ++ j)
+	if (large_allocs[i].ptr1 == large_allocs[j].ptr2)
+	  ok = 1;
+      if (ok == 1)
+	count ++;
+    }
+
+  /* The allocation algorithm is complicated outside of the memalign
+     logic, so just make sure it's working for most of the
+     allocations.  This avoids possible boundary conditions with
+     empty/full heaps.  */
+  TEST_VERIFY (count > LN / 2);
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  pthread_t p;
+
+  p = xpthread_create (NULL, mem_test, NULL);
+  xpthread_join (p);
+  return 0;
+}
+
+#include <support/test-driver.c>