From: Song Liu <songliubraving@fb.com>
To: <linux-mm@kvack.org>, <linux-fsdevel@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: <matthew.wilcox@oracle.com>, <kirill.shutemov@linux.intel.com>,
<kernel-team@fb.com>, <william.kucharski@oracle.com>,
<akpm@linux-foundation.org>, <hdanton@sina.com>,
Song Liu <songliubraving@fb.com>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: [PATCH v10 6/7] mm,thp: add read-only THP support for (non-shmem) FS
Date: Thu, 1 Aug 2019 11:42:43 -0700 [thread overview]
Message-ID: <20190801184244.3169074-7-songliubraving@fb.com> (raw)
In-Reply-To: <20190801184244.3169074-1-songliubraving@fb.com>
This patch is (hopefully) the first step to enable THP for non-shmem
filesystems.
This patch enables an application to put part of its text sections to THP
via madvise, for example:
madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE);
We tried to reuse the logic for THP on tmpfs.
Currently, write is not supported for non-shmem THP. khugepaged will only
process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests
(see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is
execve(). This requirement limits non-shmem THP to text sections.
The next patch will handle writes, which would only happen when the all
the vmas with VM_DENYWRITE are unmapped.
An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this
feature.
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
mm/Kconfig | 11 ++++
mm/filemap.c | 4 +-
mm/khugepaged.c | 149 ++++++++++++++++++++++++++++++++++--------------
mm/rmap.c | 12 ++--
4 files changed, 128 insertions(+), 48 deletions(-)
diff --git a/mm/Kconfig b/mm/Kconfig
index 56cec636a1fc..06f758786e4a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -723,6 +723,17 @@ config GUP_BENCHMARK
config GUP_GET_PTE_LOW_HIGH
bool
+config READ_ONLY_THP_FOR_FS
+ bool "Read-only THP for filesystems (EXPERIMENTAL)"
+ depends on TRANSPARENT_HUGE_PAGECACHE && SHMEM
+
+ help
+ Allow khugepaged to put read-only file-backed pages in THP.
+
+ This is marked experimental because it is a new feature. Write
+ support of file THPs will be developed in the next few release
+ cycles.
+
config ARCH_HAS_PTE_SPECIAL
bool
diff --git a/mm/filemap.c b/mm/filemap.c
index 97c7b7b92c20..0b8b117dbed6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -203,8 +203,8 @@ static void unaccount_page_cache_page(struct address_space *mapping,
__mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr);
if (PageTransHuge(page))
__dec_node_page_state(page, NR_SHMEM_THPS);
- } else {
- VM_BUG_ON_PAGE(PageTransHuge(page), page);
+ } else if (PageTransHuge(page)) {
+ __dec_node_page_state(page, NR_FILE_THPS);
}
/*
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 9d3cc2061960..8fb26856a7e9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -48,6 +48,7 @@ enum scan_result {
SCAN_CGROUP_CHARGE_FAIL,
SCAN_EXCEED_SWAP_PTE,
SCAN_TRUNCATED,
+ SCAN_PAGE_HAS_PRIVATE,
};
#define CREATE_TRACE_POINTS
@@ -410,7 +411,11 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
(vm_flags & VM_NOHUGEPAGE) ||
test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
return false;
- if (shmem_file(vma->vm_file)) {
+
+ if (shmem_file(vma->vm_file) ||
+ (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
+ vma->vm_file &&
+ (vm_flags & VM_DENYWRITE))) {
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
return false;
return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
@@ -462,8 +467,9 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long hstart, hend;
/*
- * khugepaged does not yet work on non-shmem files or special
- * mappings. And file-private shmem THP is not supported.
+ * khugepaged only supports read-only files for non-shmem files.
+ * khugepaged does not yet work on special mappings. And
+ * file-private shmem THP is not supported.
*/
if (!hugepage_vma_check(vma, vm_flags))
return 0;
@@ -1426,12 +1432,12 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
}
/**
- * collapse_file - collapse small tmpfs/shmem pages into huge one.
+ * collapse_file - collapse filemap/tmpfs/shmem pages into huge one.
*
* Basic scheme is simple, details are more complex:
* - allocate and lock a new huge page;
* - scan page cache replacing old pages with the new one
- * + swap in pages if necessary;
+ * + swap/gup in pages if necessary;
* + fill in gaps;
* + keep old pages around in case rollback is required;
* - if replacing succeeds:
@@ -1455,7 +1461,9 @@ static void collapse_file(struct mm_struct *mm,
LIST_HEAD(pagelist);
XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
int nr_none = 0, result = SCAN_SUCCEED;
+ bool is_shmem = shmem_file(file);
+ VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
/* Only allocate from the target node */
@@ -1487,7 +1495,8 @@ static void collapse_file(struct mm_struct *mm,
} while (1);
__SetPageLocked(new_page);
- __SetPageSwapBacked(new_page);
+ if (is_shmem)
+ __SetPageSwapBacked(new_page);
new_page->index = start;
new_page->mapping = mapping;
@@ -1502,41 +1511,75 @@ static void collapse_file(struct mm_struct *mm,
struct page *page = xas_next(&xas);
VM_BUG_ON(index != xas.xa_index);
- if (!page) {
- /*
- * Stop if extent has been truncated or hole-punched,
- * and is now completely empty.
- */
- if (index == start) {
- if (!xas_next_entry(&xas, end - 1)) {
- result = SCAN_TRUNCATED;
+ if (is_shmem) {
+ if (!page) {
+ /*
+ * Stop if extent has been truncated or
+ * hole-punched, and is now completely
+ * empty.
+ */
+ if (index == start) {
+ if (!xas_next_entry(&xas, end - 1)) {
+ result = SCAN_TRUNCATED;
+ goto xa_locked;
+ }
+ xas_set(&xas, index);
+ }
+ if (!shmem_charge(mapping->host, 1)) {
+ result = SCAN_FAIL;
goto xa_locked;
}
- xas_set(&xas, index);
+ xas_store(&xas, new_page);
+ nr_none++;
+ continue;
}
- if (!shmem_charge(mapping->host, 1)) {
- result = SCAN_FAIL;
+
+ if (xa_is_value(page) || !PageUptodate(page)) {
+ xas_unlock_irq(&xas);
+ /* swap in or instantiate fallocated page */
+ if (shmem_getpage(mapping->host, index, &page,
+ SGP_NOHUGE)) {
+ result = SCAN_FAIL;
+ goto xa_unlocked;
+ }
+ } else if (trylock_page(page)) {
+ get_page(page);
+ xas_unlock_irq(&xas);
+ } else {
+ result = SCAN_PAGE_LOCK;
goto xa_locked;
}
- xas_store(&xas, new_page);
- nr_none++;
- continue;
- }
-
- if (xa_is_value(page) || !PageUptodate(page)) {
- xas_unlock_irq(&xas);
- /* swap in or instantiate fallocated page */
- if (shmem_getpage(mapping->host, index, &page,
- SGP_NOHUGE)) {
+ } else { /* !is_shmem */
+ if (!page || xa_is_value(page)) {
+ xas_unlock_irq(&xas);
+ page_cache_sync_readahead(mapping, &file->f_ra,
+ file, index,
+ PAGE_SIZE);
+ /* drain pagevecs to help isolate_lru_page() */
+ lru_add_drain();
+ page = find_lock_page(mapping, index);
+ if (unlikely(page == NULL)) {
+ result = SCAN_FAIL;
+ goto xa_unlocked;
+ }
+ } else if (!PageUptodate(page)) {
+ xas_unlock_irq(&xas);
+ wait_on_page_locked(page);
+ if (!trylock_page(page)) {
+ result = SCAN_PAGE_LOCK;
+ goto xa_unlocked;
+ }
+ get_page(page);
+ } else if (PageDirty(page)) {
result = SCAN_FAIL;
- goto xa_unlocked;
+ goto xa_locked;
+ } else if (trylock_page(page)) {
+ get_page(page);
+ xas_unlock_irq(&xas);
+ } else {
+ result = SCAN_PAGE_LOCK;
+ goto xa_locked;
}
- } else if (trylock_page(page)) {
- get_page(page);
- xas_unlock_irq(&xas);
- } else {
- result = SCAN_PAGE_LOCK;
- goto xa_locked;
}
/*
@@ -1565,6 +1608,12 @@ static void collapse_file(struct mm_struct *mm,
goto out_unlock;
}
+ if (page_has_private(page) &&
+ !try_to_release_page(page, GFP_KERNEL)) {
+ result = SCAN_PAGE_HAS_PRIVATE;
+ break;
+ }
+
if (page_mapped(page))
unmap_mapping_pages(mapping, index, 1, false);
@@ -1602,12 +1651,18 @@ static void collapse_file(struct mm_struct *mm,
goto xa_unlocked;
}
- __inc_node_page_state(new_page, NR_SHMEM_THPS);
+ if (is_shmem)
+ __inc_node_page_state(new_page, NR_SHMEM_THPS);
+ else
+ __inc_node_page_state(new_page, NR_FILE_THPS);
+
if (nr_none) {
struct zone *zone = page_zone(new_page);
__mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
- __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
+ if (is_shmem)
+ __mod_node_page_state(zone->zone_pgdat,
+ NR_SHMEM, nr_none);
}
xa_locked:
@@ -1645,10 +1700,15 @@ static void collapse_file(struct mm_struct *mm,
SetPageUptodate(new_page);
page_ref_add(new_page, HPAGE_PMD_NR - 1);
- set_page_dirty(new_page);
mem_cgroup_commit_charge(new_page, memcg, false, true);
+
+ if (is_shmem) {
+ set_page_dirty(new_page);
+ lru_cache_add_anon(new_page);
+ } else {
+ lru_cache_add_file(new_page);
+ }
count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1);
- lru_cache_add_anon(new_page);
/*
* Remove pte page tables, so we can re-fault the page as huge.
@@ -1663,7 +1723,9 @@ static void collapse_file(struct mm_struct *mm,
/* Something went wrong: roll back page cache changes */
xas_lock_irq(&xas);
mapping->nrpages -= nr_none;
- shmem_uncharge(mapping->host, nr_none);
+
+ if (is_shmem)
+ shmem_uncharge(mapping->host, nr_none);
xas_set(&xas, start);
xas_for_each(&xas, page, end - 1) {
@@ -1746,7 +1808,8 @@ static void khugepaged_scan_file(struct mm_struct *mm,
break;
}
- if (page_count(page) != 1 + page_mapcount(page)) {
+ if (page_count(page) !=
+ 1 + page_mapcount(page) + page_has_private(page)) {
result = SCAN_PAGE_COUNT;
break;
}
@@ -1853,11 +1916,13 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
VM_BUG_ON(khugepaged_scan.address < hstart ||
khugepaged_scan.address + HPAGE_PMD_SIZE >
hend);
- if (shmem_file(vma->vm_file)) {
+ if (vma->vm_file) {
struct file *file;
pgoff_t pgoff = linear_page_index(vma,
khugepaged_scan.address);
- if (!shmem_huge_enabled(vma))
+
+ if (shmem_file(vma->vm_file)
+ && !shmem_huge_enabled(vma))
goto skip;
file = get_file(vma->vm_file);
up_read(&mm->mmap_sem);
diff --git a/mm/rmap.c b/mm/rmap.c
index e5dfe2ae6b0d..87cfa2c19eda 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1192,8 +1192,10 @@ void page_add_file_rmap(struct page *page, bool compound)
}
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
goto out;
- VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
- __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ if (PageSwapBacked(page))
+ __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ else
+ __inc_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
if (PageTransCompound(page) && page_mapping(page)) {
VM_WARN_ON_ONCE(!PageLocked(page));
@@ -1232,8 +1234,10 @@ static void page_remove_file_rmap(struct page *page, bool compound)
}
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
goto out;
- VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
- __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ if (PageSwapBacked(page))
+ __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
+ else
+ __dec_node_page_state(page, NR_FILE_PMDMAPPED);
} else {
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;
--
2.17.1
next prev parent reply other threads:[~2019-08-01 18:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 18:42 [PATCH v10 0/7] Enable THP for text section of non-shmem files Song Liu
2019-08-01 18:42 ` [PATCH v10 1/7] filemap: check compound_head(page)->mapping in filemap_fault() Song Liu
2019-08-01 18:42 ` [PATCH v10 2/7] filemap: check compound_head(page)->mapping in pagecache_get_page() Song Liu
2019-08-12 20:33 ` Johannes Weiner
2019-08-01 18:42 ` [PATCH v10 3/7] filemap: update offset check in filemap_fault() Song Liu
2019-08-01 18:42 ` [PATCH v10 4/7] mm,thp: stats for file backed THP Song Liu
2019-08-01 18:42 ` [PATCH v10 5/7] khugepaged: rename collapse_shmem() and khugepaged_scan_shmem() Song Liu
2019-08-01 18:42 ` Song Liu [this message]
2019-08-12 20:36 ` [PATCH v10 6/7] mm,thp: add read-only THP support for (non-shmem) FS Johannes Weiner
2019-08-01 18:42 ` [PATCH v10 7/7] mm,thp: avoid writes to file with THP in pagecache Song Liu
2019-08-12 20:38 ` Johannes Weiner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190801184244.3169074-7-songliubraving@fb.com \
--to=songliubraving@fb.com \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=hdanton@sina.com \
--cc=kernel-team@fb.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.wilcox@oracle.com \
--cc=william.kucharski@oracle.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.