Detect kernels that honor gfp flags passed to vmalloc()

zfsonlinux/spl@2092cf68d8 used
PF_MEMALLOC to workaround a bug in the Linux kernel where
allocations did not honor the gfp flags passed to vmalloc().
Unfortunately, PF_MEMALLOC has the side effect of permitting
allocations to allocate pages outside of ZONE_NORMAL. This
has been observed to result in the depletion of ZONE_DMA32.

A kernel patch is available in the Gentoo bug tracker for
this issue.

  https://bugs.gentoo.org/show_bug.cgi?id=416685

This negates any benefit PF_MEMALLOC provides, so we introduce
an autotools check to disable the use of PF_MEMALLOC on
systems with patched kernels.

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #126
This commit is contained in:
Richard Yao 2012-06-06 22:38:12 -04:00 committed by Brian Behlendorf
parent 973e8269bd
commit 36811b4430
4 changed files with 199 additions and 0 deletions

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@ -88,6 +88,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
SPL_AC_2ARGS_ZLIB_DEFLATE_WORKSPACESIZE SPL_AC_2ARGS_ZLIB_DEFLATE_WORKSPACESIZE
SPL_AC_SHRINK_CONTROL_STRUCT SPL_AC_SHRINK_CONTROL_STRUCT
SPL_AC_RWSEM_SPINLOCK_IS_RAW SPL_AC_RWSEM_SPINLOCK_IS_RAW
SPL_AC_PMD_ALLOC_WITH_MASK
]) ])
AC_DEFUN([SPL_AC_MODULE_SYMVERS], [ AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
@ -2079,3 +2080,38 @@ AC_DEFUN([SPL_AC_RWSEM_SPINLOCK_IS_RAW], [
]) ])
EXTRA_KCFLAGS="$tmp_flags" EXTRA_KCFLAGS="$tmp_flags"
]) ])
dnl #
dnl # Proposed VM Subsystem Bug Fix
dnl # https://bugs.gentoo.org/show_bug.cgi?id=416685
dnl #
dnl # Make __pte_alloc_kernel() honor gfp flags passed to vmalloc()
dnl # This is detected by checking a macro that is changed to support this.
dnl #
AC_DEFUN([SPL_AC_PMD_ALLOC_WITH_MASK], [
AC_MSG_CHECKING([whether pmd_alloc_with_mask exists])
SPL_LINUX_TRY_COMPILE([
#if !defined(CONFIG_MMU)
#define CONFIG_MMU
#endif
#if defined(RCH_HAS_4LEVEL_HACK)
#undef RCH_HAS_4LEVEL_HACK
#endif
#include <linux/mm.h>
],[
struct mm_struct init_mm;
pud_t *pud = NULL;
unsigned long addr = 0;
gfp_t gfp_mask = GFP_KERNEL;
pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_PMD_ALLOC_WITH_MASK, 1,
[pmd_alloc_with_mask exists])
],[
AC_MSG_RESULT(no)
])
])

156
configure vendored
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@ -16231,6 +16231,84 @@ fi
EXTRA_KCFLAGS="$tmp_flags" EXTRA_KCFLAGS="$tmp_flags"
{ $as_echo "$as_me:$LINENO: checking whether pmd_alloc_with_mask exists" >&5
$as_echo_n "checking whether pmd_alloc_with_mask exists... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#if !defined(CONFIG_MMU)
#define CONFIG_MMU
#endif
#if defined(RCH_HAS_4LEVEL_HACK)
#undef RCH_HAS_4LEVEL_HACK
#endif
#include <linux/mm.h>
int
main (void)
{
struct mm_struct init_mm;
pud_t *pud = NULL;
unsigned long addr = 0;
gfp_t gfp_mask = GFP_KERNEL;
pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_PMD_ALLOC_WITH_MASK 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
;; ;;
user) ;; user) ;;
all) all)
@ -20730,6 +20808,84 @@ fi
EXTRA_KCFLAGS="$tmp_flags" EXTRA_KCFLAGS="$tmp_flags"
{ $as_echo "$as_me:$LINENO: checking whether pmd_alloc_with_mask exists" >&5
$as_echo_n "checking whether pmd_alloc_with_mask exists... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#if !defined(CONFIG_MMU)
#define CONFIG_MMU
#endif
#if defined(RCH_HAS_4LEVEL_HACK)
#undef RCH_HAS_4LEVEL_HACK
#endif
#include <linux/mm.h>
int
main (void)
{
struct mm_struct init_mm;
pud_t *pud = NULL;
unsigned long addr = 0;
gfp_t gfp_mask = GFP_KERNEL;
pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_PMD_ALLOC_WITH_MASK 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
;; ;;
srpm) ;; srpm) ;;
*) *)

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@ -843,6 +843,9 @@ kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
if (skc->skc_flags & KMC_KMEM) { if (skc->skc_flags & KMC_KMEM) {
ptr = (void *)__get_free_pages(flags, get_order(size)); ptr = (void *)__get_free_pages(flags, get_order(size));
} else { } else {
#ifdef HAVE_PMD_ALLOC_WITH_MASK
ptr = __vmalloc(size, flags|__GFP_HIGHMEM, PAGE_KERNEL);
#else
/* /*
* As part of vmalloc() an __pte_alloc_kernel() allocation * As part of vmalloc() an __pte_alloc_kernel() allocation
* may occur. This internal allocation does not honor the * may occur. This internal allocation does not honor the
@ -866,6 +869,7 @@ kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
} else { } else {
ptr = __vmalloc(size, flags|__GFP_HIGHMEM, PAGE_KERNEL); ptr = __vmalloc(size, flags|__GFP_HIGHMEM, PAGE_KERNEL);
} }
#endif
} }
/* Resulting allocated memory will be page aligned */ /* Resulting allocated memory will be page aligned */

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@ -165,6 +165,9 @@
/* pgdat_list is available */ /* pgdat_list is available */
#undef HAVE_PGDAT_LIST #undef HAVE_PGDAT_LIST
/* pmd_alloc_with_mask exists */
#undef HAVE_PMD_ALLOC_WITH_MASK
/* __put_task_struct() is available */ /* __put_task_struct() is available */
#undef HAVE_PUT_TASK_STRUCT #undef HAVE_PUT_TASK_STRUCT