The patch titled
Subject: mm, THP, swap: add sysfs interface to configure THP swapin
has been added to the -mm tree. Its filename is
mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: mm, THP, swap: add sysfs interface to configure THP swapin
Swapin a THP as a whole isn't desirable at some situations. For example,
for random access pattern, swapin a THP as a whole will inflate the
reading greatly. So a sysfs interface:
/sys/kernel/mm/transparent_hugepage/swapin_enabled is added to configure
it. Three options as follow are provided,
- always: THP swapin will be enabled always
- madvise: THP swapin will be enabled only for VMA with VM_HUGEPAGE
flag set.
- never: THP swapin will be disabled always
The default configuration is: madvise.
During page fault, if a PMD swap mapping is found and THP swapin is
disabled, the huge swap cluster and the PMD swap mapping will be split and
fallback to normal page swapin.
Link: http://lkml.kernel.org/r/20180622035151.6676-12-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN Documentation/admin-guide/mm/transhuge.rst~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin Documentation/admin-guide/mm/transhuge.rst
--- a/Documentation/admin-guide/mm/transhuge.rst~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin
+++ a/Documentation/admin-guide/mm/transhuge.rst
@@ -160,6 +160,27 @@ library) may want to know the size (in b
cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
+Transparent hugepage may be swapout and swapin in one piece without
+splitting. This will improve the utility of transparent hugepage but
+may inflate the read/write too. So whether to enable swapin
+transparent hugepage in one piece can be configured as follow.
+
+ echo always >/sys/kernel/mm/transparent_hugepage/swapin_enabled
+ echo madvise >/sys/kernel/mm/transparent_hugepage/swapin_enabled
+ echo never >/sys/kernel/mm/transparent_hugepage/swapin_enabled
+
+always
+ Attempt to allocate a transparent huge page and read it from
+ swap space in one piece every time.
+
+never
+ Always split the swap space and PMD swap mapping and swapin
+ the fault normal page during swapin.
+
+madvise
+ Only swapin the transparent huge page in one piece for
+ MADV_HUGEPAGE madvise regions.
+
khugepaged will be automatically started when
transparent_hugepage/enabled is set to "always" or "madvise, and it'll
be automatically shutdown if it's set to "never".
diff -puN include/linux/huge_mm.h~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin include/linux/huge_mm.h
--- a/include/linux/huge_mm.h~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin
+++ a/include/linux/huge_mm.h
@@ -62,6 +62,8 @@ enum transparent_hugepage_flag {
#ifdef CONFIG_DEBUG_VM
TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
#endif
+ TRANSPARENT_HUGEPAGE_SWAPIN_FLAG,
+ TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG,
};
struct kobject;
@@ -404,11 +406,40 @@ static inline gfp_t alloc_hugepage_direc
#ifdef CONFIG_THP_SWAP
extern int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd);
+
+static inline bool transparent_hugepage_swapin_enabled(
+ struct vm_area_struct *vma)
+{
+ if (vma->vm_flags & VM_NOHUGEPAGE)
+ return false;
+
+ if (is_vma_temporary_stack(vma))
+ return false;
+
+ if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ return false;
+
+ if (transparent_hugepage_flags &
+ (1 << TRANSPARENT_HUGEPAGE_SWAPIN_FLAG))
+ return true;
+
+ if (transparent_hugepage_flags &
+ (1 << TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG))
+ return !!(vma->vm_flags & VM_HUGEPAGE);
+
+ return false;
+}
#else /* CONFIG_THP_SWAP */
static inline int do_huge_pmd_swap_page(struct vm_fault *vmf, pmd_t orig_pmd)
{
return 0;
}
+
+static inline bool transparent_hugepage_swapin_enabled(
+ struct vm_area_struct *vma)
+{
+ return false;
+}
#endif /* CONFIG_THP_SWAP */
#endif /* _LINUX_HUGE_MM_H */
diff -puN mm/huge_memory.c~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin mm/huge_memory.c
--- a/mm/huge_memory.c~mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin
+++ a/mm/huge_memory.c
@@ -57,7 +57,8 @@ unsigned long transparent_hugepage_flags
#endif
(1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
- (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+ (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG)|
+ (1<<TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG);
static struct shrinker deferred_split_shrinker;
@@ -316,6 +317,53 @@ static struct kobj_attribute debug_cow_a
__ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
#endif /* CONFIG_DEBUG_VM */
+#ifdef CONFIG_THP_SWAP
+static ssize_t swapin_enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ if (test_bit(TRANSPARENT_HUGEPAGE_SWAPIN_FLAG,
+ &transparent_hugepage_flags))
+ return sprintf(buf, "[always] madvise never\n");
+ else if (test_bit(TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG,
+ &transparent_hugepage_flags))
+ return sprintf(buf, "always [madvise] never\n");
+ else
+ return sprintf(buf, "always madvise [never]\n");
+}
+
+static ssize_t swapin_enabled_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ ssize_t ret = count;
+
+ if (!memcmp("always", buf,
+ min(sizeof("always")-1, count))) {
+ clear_bit(TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_SWAPIN_FLAG,
+ &transparent_hugepage_flags);
+ } else if (!memcmp("madvise", buf,
+ min(sizeof("madvise")-1, count))) {
+ clear_bit(TRANSPARENT_HUGEPAGE_SWAPIN_FLAG,
+ &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ } else if (!memcmp("never", buf,
+ min(sizeof("never")-1, count))) {
+ clear_bit(TRANSPARENT_HUGEPAGE_SWAPIN_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_SWAPIN_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ } else
+ ret = -EINVAL;
+
+ return ret;
+}
+static struct kobj_attribute swapin_enabled_attr =
+ __ATTR(swapin_enabled, 0644, swapin_enabled_show, swapin_enabled_store);
+#endif /* CONFIG_THP_SWAP */
+
static struct attribute *hugepage_attr[] = {
&enabled_attr.attr,
&defrag_attr.attr,
@@ -327,6 +375,9 @@ static struct attribute *hugepage_attr[]
#ifdef CONFIG_DEBUG_VM
&debug_cow_attr.attr,
#endif
+#ifdef CONFIG_THP_SWAP
+ &swapin_enabled_attr.attr,
+#endif
NULL,
};
@@ -1646,6 +1697,9 @@ int do_huge_pmd_swap_page(struct vm_faul
retry:
page = lookup_swap_cache(entry, NULL, vmf->address);
if (!page) {
+ if (!transparent_hugepage_swapin_enabled(vma))
+ goto split;
+
page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE, vma,
haddr, false);
if (!page) {
@@ -1653,23 +1707,8 @@ retry:
* Back out if somebody else faulted in this pmd
* while we released the pmd lock.
*/
- if (likely(pmd_same(*vmf->pmd, orig_pmd))) {
- ret = split_swap_cluster(entry, false);
- /*
- * Retry if somebody else swap in the swap
- * entry
- */
- if (ret == -EEXIST) {
- ret = 0;
- goto retry;
- /* swapoff occurs under us */
- } else if (ret == -EINVAL)
- ret = 0;
- else {
- count_vm_event(THP_SWPIN_FALLBACK);
- goto fallback;
- }
- }
+ if (likely(pmd_same(*vmf->pmd, orig_pmd)))
+ goto split;
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
goto out;
}
@@ -1781,6 +1820,20 @@ fallback:
if (page)
put_page(page);
return ret;
+split:
+ ret = split_swap_cluster(entry, false);
+ /* Retry if somebody else swap in the swap entry */
+ if (ret == -EEXIST) {
+ ret = 0;
+ goto retry;
+ }
+ /* swapoff occurs under us */
+ if (ret == -EINVAL) {
+ delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+ return 0;
+ }
+ count_vm_event(THP_SWPIN_FALLBACK);
+ goto fallback;
}
#else
static inline void __split_huge_swap_pmd(struct vm_area_struct *vma,
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
mm-clear_huge_page-move-order-algorithm-into-a-separate-function.patch
mm-huge-page-copy-target-sub-page-last-when-copy-huge-page.patch
mm-hugetlbfs-rename-address-to-haddr-in-hugetlb_cow.patch
mm-hugetlbfs-pass-fault-address-to-cow-handler.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations-v6.patch
mm-fix-race-between-swapoff-and-mincore.patch
mm-thp-swap-enable-pmd-swap-operations-for-config_thp_swap.patch
mm-thp-swap-make-config_thp_swap-depends-on-config_swap.patch
mm-thp-swap-support-pmd-swap-mapping-in-swap_duplicate.patch
mm-thp-swap-support-pmd-swap-mapping-in-swapcache_free_cluster.patch
mm-thp-swap-support-pmd-swap-mapping-in-free_swap_and_cache-swap_free.patch
mm-thp-swap-support-pmd-swap-mapping-when-splitting-huge-pmd.patch
mm-thp-swap-support-pmd-swap-mapping-in-split_swap_cluster.patch
mm-thp-swap-support-to-read-a-huge-swap-cluster-for-swapin-a-thp.patch
mm-thp-swap-swapin-a-thp-as-a-whole.patch
mm-thp-swap-support-to-count-thp-swapin-and-its-fallback.patch
mm-thp-swap-add-sysfs-interface-to-configure-thp-swapin.patch
mm-thp-swap-support-pmd-swap-mapping-in-swapoff.patch
mm-thp-swap-support-pmd-swap-mapping-in-madvise_free.patch
mm-cgroup-thp-swap-support-to-move-swap-account-for-pmd-swap-mapping.patch
mm-thp-swap-support-to-copy-pmd-swap-mapping-when-fork.patch
mm-thp-swap-free-pmd-swap-mapping-when-zap_huge_pmd.patch
mm-thp-swap-support-pmd-swap-mapping-for-madv_willneed.patch
mm-thp-swap-support-pmd-swap-mapping-in-mincore.patch
mm-thp-swap-support-pmd-swap-mapping-in-common-path.patch
mm-thp-swap-create-pmd-swap-mapping-when-unmap-the-thp.patch
mm-thp-avoid-to-split-thp-when-reclaim-madv_free-thp.patch
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