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
Brian Behlendorf
parent
973e8269bd
commit
36811b4430
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@ -88,6 +88,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
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SPL_AC_2ARGS_ZLIB_DEFLATE_WORKSPACESIZE
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SPL_AC_SHRINK_CONTROL_STRUCT
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SPL_AC_RWSEM_SPINLOCK_IS_RAW
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SPL_AC_PMD_ALLOC_WITH_MASK
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])
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AC_DEFUN([SPL_AC_MODULE_SYMVERS], [
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@ -2079,3 +2080,38 @@ AC_DEFUN([SPL_AC_RWSEM_SPINLOCK_IS_RAW], [
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])
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EXTRA_KCFLAGS="$tmp_flags"
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])
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dnl #
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dnl # Proposed VM Subsystem Bug Fix
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dnl # https://bugs.gentoo.org/show_bug.cgi?id=416685
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dnl #
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dnl # Make __pte_alloc_kernel() honor gfp flags passed to vmalloc()
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dnl # This is detected by checking a macro that is changed to support this.
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dnl #
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AC_DEFUN([SPL_AC_PMD_ALLOC_WITH_MASK], [
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AC_MSG_CHECKING([whether pmd_alloc_with_mask exists])
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SPL_LINUX_TRY_COMPILE([
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#if !defined(CONFIG_MMU)
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#define CONFIG_MMU
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#endif
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#if defined(RCH_HAS_4LEVEL_HACK)
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#undef RCH_HAS_4LEVEL_HACK
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#endif
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#include <linux/mm.h>
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],[
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struct mm_struct init_mm;
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pud_t *pud = NULL;
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unsigned long addr = 0;
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gfp_t gfp_mask = GFP_KERNEL;
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pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
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],[
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AC_MSG_RESULT(yes)
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AC_DEFINE(HAVE_PMD_ALLOC_WITH_MASK, 1,
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[pmd_alloc_with_mask exists])
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],[
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AC_MSG_RESULT(no)
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])
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])
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@ -16231,6 +16231,84 @@ fi
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EXTRA_KCFLAGS="$tmp_flags"
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{ $as_echo "$as_me:$LINENO: checking whether pmd_alloc_with_mask exists" >&5
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$as_echo_n "checking whether pmd_alloc_with_mask exists... " >&6; }
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cat confdefs.h - <<_ACEOF >conftest.c
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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cat >>conftest.$ac_ext <<_ACEOF
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/* end confdefs.h. */
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#if !defined(CONFIG_MMU)
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#define CONFIG_MMU
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#endif
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#if defined(RCH_HAS_4LEVEL_HACK)
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#undef RCH_HAS_4LEVEL_HACK
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#endif
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#include <linux/mm.h>
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int
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main (void)
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{
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struct mm_struct init_mm;
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pud_t *pud = NULL;
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unsigned long addr = 0;
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gfp_t gfp_mask = GFP_KERNEL;
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pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
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;
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return 0;
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}
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_ACEOF
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rm -Rf build && mkdir -p build
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echo "obj-m := conftest.o" >build/Makefile
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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'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; }; then
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{ $as_echo "$as_me:$LINENO: result: yes" >&5
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$as_echo "yes" >&6; }
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cat >>confdefs.h <<\_ACEOF
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#define HAVE_PMD_ALLOC_WITH_MASK 1
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_ACEOF
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else
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$as_echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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{ $as_echo "$as_me:$LINENO: result: no" >&5
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$as_echo "no" >&6; }
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fi
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rm -Rf build
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;;
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user) ;;
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all)
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@ -20730,6 +20808,84 @@ fi
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EXTRA_KCFLAGS="$tmp_flags"
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{ $as_echo "$as_me:$LINENO: checking whether pmd_alloc_with_mask exists" >&5
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$as_echo_n "checking whether pmd_alloc_with_mask exists... " >&6; }
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cat confdefs.h - <<_ACEOF >conftest.c
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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cat >>conftest.$ac_ext <<_ACEOF
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/* end confdefs.h. */
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#if !defined(CONFIG_MMU)
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#define CONFIG_MMU
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#endif
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#if defined(RCH_HAS_4LEVEL_HACK)
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#undef RCH_HAS_4LEVEL_HACK
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#endif
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#include <linux/mm.h>
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int
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main (void)
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{
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struct mm_struct init_mm;
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pud_t *pud = NULL;
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unsigned long addr = 0;
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gfp_t gfp_mask = GFP_KERNEL;
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pmd_alloc_with_mask(&init_mm, pud, addr, gfp_mask);
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;
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return 0;
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}
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_ACEOF
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rm -Rf build && mkdir -p build
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echo "obj-m := conftest.o" >build/Makefile
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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'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; }; then
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{ $as_echo "$as_me:$LINENO: result: yes" >&5
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$as_echo "yes" >&6; }
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cat >>confdefs.h <<\_ACEOF
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#define HAVE_PMD_ALLOC_WITH_MASK 1
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_ACEOF
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else
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$as_echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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{ $as_echo "$as_me:$LINENO: result: no" >&5
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$as_echo "no" >&6; }
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fi
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rm -Rf build
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;;
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srpm) ;;
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*)
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@ -843,6 +843,9 @@ kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
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if (skc->skc_flags & KMC_KMEM) {
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ptr = (void *)__get_free_pages(flags, get_order(size));
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} else {
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#ifdef HAVE_PMD_ALLOC_WITH_MASK
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ptr = __vmalloc(size, flags|__GFP_HIGHMEM, PAGE_KERNEL);
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#else
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/*
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* As part of vmalloc() an __pte_alloc_kernel() allocation
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* may occur. This internal allocation does not honor the
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@ -866,6 +869,7 @@ kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
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} else {
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ptr = __vmalloc(size, flags|__GFP_HIGHMEM, PAGE_KERNEL);
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}
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#endif
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}
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/* Resulting allocated memory will be page aligned */
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@ -165,6 +165,9 @@
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/* pgdat_list is available */
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#undef HAVE_PGDAT_LIST
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/* pmd_alloc_with_mask exists */
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#undef HAVE_PMD_ALLOC_WITH_MASK
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/* __put_task_struct() is available */
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#undef HAVE_PUT_TASK_STRUCT
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