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Groups > linux.kernel > #1730616 > unrolled thread

[PATCH 1/5] zram: set BDI_CAP_STABLE_WRITES once

Started byMinchan Kim <minchan@kernel.org>
First post2017-09-12 04:40 +0200
Last post2017-09-12 06:50 +0200
Articles 7 — 2 participants

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  [PATCH 1/5] zram: set BDI_CAP_STABLE_WRITES once Minchan Kim <minchan@kernel.org> - 2017-09-12 04:40 +0200
    [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device Minchan Kim <minchan@kernel.org> - 2017-09-12 04:40 +0200
      Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous  device Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-12 08:10 +0200
        Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous  device Minchan Kim <minchan@kernel.org> - 2017-09-12 08:40 +0200
      Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous  device Minchan Kim <minchan@kernel.org> - 2017-09-13 02:20 +0200
    [PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO Minchan Kim <minchan@kernel.org> - 2017-09-12 04:40 +0200
      Re: [PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-12 06:50 +0200

#1730616 — [PATCH 1/5] zram: set BDI_CAP_STABLE_WRITES once

FromMinchan Kim <minchan@kernel.org>
Date2017-09-12 04:40 +0200
Subject[PATCH 1/5] zram: set BDI_CAP_STABLE_WRITES once
Message-ID<uoJhf-3C9-5@gated-at.bofh.it>
[1] fixed weird thing(i.e., reset BDI_CAP_STABLE_WRITES flag
unconditionally whenever revalidat_disk is called) so zram doesn't
need to reset the flag any more whenever revalidating the bdev.
Instead, set the flag just once when the zram device is created.

It shouldn't change any behavior.

[1] 19b7ccf8651d, block: get rid of blk_integrity_revalidate()
Cc: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 drivers/block/zram/zram_drv.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 2981c27d3aae..ba009675fdc0 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -122,14 +122,6 @@ static inline bool is_partial_io(struct bio_vec *bvec)
 }
 #endif
 
-static void zram_revalidate_disk(struct zram *zram)
-{
-	revalidate_disk(zram->disk);
-	/* revalidate_disk reset the BDI_CAP_STABLE_WRITES so set again */
-	zram->disk->queue->backing_dev_info->capabilities |=
-		BDI_CAP_STABLE_WRITES;
-}
-
 /*
  * Check if request is within bounds and aligned on zram logical blocks.
  */
@@ -1385,7 +1377,8 @@ static ssize_t disksize_store(struct device *dev,
 	zram->comp = comp;
 	zram->disksize = disksize;
 	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-	zram_revalidate_disk(zram);
+
+	revalidate_disk(zram->disk);
 	up_write(&zram->init_lock);
 
 	return len;
@@ -1432,7 +1425,7 @@ static ssize_t reset_store(struct device *dev,
 	/* Make sure all the pending I/O are finished */
 	fsync_bdev(bdev);
 	zram_reset_device(zram);
-	zram_revalidate_disk(zram);
+	revalidate_disk(zram->disk);
 	bdput(bdev);
 
 	mutex_lock(&bdev->bd_mutex);
@@ -1551,6 +1544,7 @@ static int zram_add(void)
 	/* zram devices sort of resembles non-rotational disks */
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
+
 	/*
 	 * To ensure that we always get PAGE_SIZE aligned
 	 * and n*PAGE_SIZED sized I/O requests.
@@ -1575,6 +1569,8 @@ static int zram_add(void)
 	if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
 		blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
 
+	zram->disk->queue->backing_dev_info->capabilities |=
+					BDI_CAP_STABLE_WRITES;
 	add_disk(zram->disk);
 
 	ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
-- 
2.7.4

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#1730617 — [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device

FromMinchan Kim <minchan@kernel.org>
Date2017-09-12 04:40 +0200
Subject[PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device
Message-ID<uoJhf-3C9-9@gated-at.bofh.it>
In reply to#1730616
With fast swap storage, platform want to use swap more aggressively
and swap-in is crucial to application latency.

The rw_page based synchronous devices like zram, pmem and btt are such
fast storage. When I profile swapin performance with zram lz4 decompress
test, S/W overhead is more than 70%. Maybe, it would be bigger in nvdimm.

This patch aims for reducing swap-in latency via skipping swapcache
if swap device is synchronous device like rw_page based device.
It enhances 45% my swapin test(5G sequential swapin, no readahead,
from 2.41sec to 1.64sec).

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/swap.h |  1 +
 mm/memory.c          | 48 +++++++++++++++++++++++++++++++++---------------
 mm/page_io.c         |  6 +++---
 mm/swapfile.c        | 11 +++++++----
 4 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 739d94397c47..fb46a3b55d65 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -462,6 +462,7 @@ extern int page_swapcount(struct page *);
 extern int __swp_swapcount(swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
 extern struct swap_info_struct *page_swap_info(struct page *);
+extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
 extern bool reuse_swap_page(struct page *, int *);
 extern int try_to_free_swap(struct page *);
 struct backing_dev_info;
diff --git a/mm/memory.c b/mm/memory.c
index ec4e15494901..130698cd2d98 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2842,7 +2842,7 @@ EXPORT_SYMBOL(unmap_mapping_range);
 int do_swap_page(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
-	struct page *page = NULL, *swapcache;
+	struct page *page = NULL, *swapcache = NULL;
 	struct mem_cgroup *memcg;
 	struct vma_swap_readahead swap_ra;
 	swp_entry_t entry;
@@ -2881,17 +2881,33 @@ int do_swap_page(struct vm_fault *vmf)
 		}
 		goto out;
 	}
+
+
 	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
 	if (!page)
 		page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
 					 vmf->address);
 	if (!page) {
-		if (vma_readahead)
-			page = do_swap_page_readahead(entry,
-				GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
-		else
-			page = swapin_readahead(entry,
-				GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+		struct swap_info_struct *si = swp_swap_info(entry);
+
+		if (!(si->flags & SWP_SYNCHRONOUS_IO)) {
+			if (vma_readahead)
+				page = do_swap_page_readahead(entry,
+					GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
+			else
+				page = swapin_readahead(entry,
+					GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+			swapcache = page;
+		} else {
+			/* skip swapcache */
+			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+			__SetPageLocked(page);
+			__SetPageSwapBacked(page);
+			set_page_private(page, entry.val);
+			lru_cache_add_anon(page);
+			swap_readpage(page, true);
+		}
+
 		if (!page) {
 			/*
 			 * Back out if somebody else faulted in this pte
@@ -2920,7 +2936,6 @@ int do_swap_page(struct vm_fault *vmf)
 		goto out_release;
 	}
 
-	swapcache = page;
 	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
 
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
@@ -2935,7 +2950,8 @@ int do_swap_page(struct vm_fault *vmf)
 	 * test below, are not enough to exclude that.  Even if it is still
 	 * swapcache, we need to check that the page's swap has not changed.
 	 */
-	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
+	if (unlikely((!PageSwapCache(page) ||
+			page_private(page) != entry.val)) && swapcache)
 		goto out_page;
 
 	page = ksm_might_need_to_copy(page, vma, vmf->address);
@@ -2988,14 +3004,16 @@ int do_swap_page(struct vm_fault *vmf)
 		pte = pte_mksoft_dirty(pte);
 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
 	vmf->orig_pte = pte;
-	if (page == swapcache) {
-		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
-		mem_cgroup_commit_charge(page, memcg, true, false);
-		activate_page(page);
-	} else { /* ksm created a completely new copy */
+
+	/* ksm created a completely new copy */
+	if (unlikely(page != swapcache && swapcache)) {
 		page_add_new_anon_rmap(page, vma, vmf->address, false);
 		mem_cgroup_commit_charge(page, memcg, false, false);
 		lru_cache_add_active_or_unevictable(page, vma);
+	} else {
+		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
+		mem_cgroup_commit_charge(page, memcg, true, false);
+		activate_page(page);
 	}
 
 	swap_free(entry);
@@ -3003,7 +3021,7 @@ int do_swap_page(struct vm_fault *vmf)
 	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
 		try_to_free_swap(page);
 	unlock_page(page);
-	if (page != swapcache) {
+	if (page != swapcache && swapcache) {
 		/*
 		 * Hold the lock to avoid the swap entry to be reused
 		 * until we take the PT lock for the pte_same() check
diff --git a/mm/page_io.c b/mm/page_io.c
index 21502d341a67..d4a98e1f6608 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -346,7 +346,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 	return ret;
 }
 
-int swap_readpage(struct page *page, bool do_poll)
+int swap_readpage(struct page *page, bool synchronous)
 {
 	struct bio *bio;
 	int ret = 0;
@@ -354,7 +354,7 @@ int swap_readpage(struct page *page, bool do_poll)
 	blk_qc_t qc;
 	struct gendisk *disk;
 
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+	VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageUptodate(page), page);
 	if (frontswap_load(page) == 0) {
@@ -402,7 +402,7 @@ int swap_readpage(struct page *page, bool do_poll)
 	count_vm_event(PSWPIN);
 	bio_get(bio);
 	qc = submit_bio(bio);
-	while (do_poll) {
+	while (synchronous) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		if (!READ_ONCE(bio->bi_private))
 			break;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1305591cde4d..64a3d85226ba 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3454,10 +3454,15 @@ int swapcache_prepare(swp_entry_t entry)
 	return __swap_duplicate(entry, SWAP_HAS_CACHE);
 }
 
+struct swap_info_struct *swp_swap_info(swp_entry_t entry)
+{
+	return swap_info[swp_type(entry)];
+}
+
 struct swap_info_struct *page_swap_info(struct page *page)
 {
-	swp_entry_t swap = { .val = page_private(page) };
-	return swap_info[swp_type(swap)];
+	swp_entry_t entry = { .val = page_private(page) };
+	return swp_swap_info(entry);
 }
 
 /*
@@ -3465,7 +3470,6 @@ struct swap_info_struct *page_swap_info(struct page *page)
  */
 struct address_space *__page_file_mapping(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return page_swap_info(page)->swap_file->f_mapping;
 }
 EXPORT_SYMBOL_GPL(__page_file_mapping);
@@ -3473,7 +3477,6 @@ EXPORT_SYMBOL_GPL(__page_file_mapping);
 pgoff_t __page_file_index(struct page *page)
 {
 	swp_entry_t swap = { .val = page_private(page) };
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return swp_offset(swap);
 }
 EXPORT_SYMBOL_GPL(__page_file_index);
-- 
2.7.4

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#1730671 — Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device

FromSergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Date2017-09-12 08:10 +0200
SubjectRe: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device
Message-ID<uoMyt-5Za-1@gated-at.bofh.it>
In reply to#1730617
On (09/12/17 11:37), Minchan Kim wrote:
> +		} else {
> +			/* skip swapcache */
> +			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);

what if alloc_page_vma() fails?

> +			__SetPageLocked(page);
> +			__SetPageSwapBacked(page);
> +			set_page_private(page, entry.val);
> +			lru_cache_add_anon(page);
> +			swap_readpage(page, true);
> +		}

	-ss

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#1730680 — Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device

FromMinchan Kim <minchan@kernel.org>
Date2017-09-12 08:40 +0200
SubjectRe: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device
Message-ID<uoN1w-6cD-17@gated-at.bofh.it>
In reply to#1730671
On Tue, Sep 12, 2017 at 03:04:56PM +0900, Sergey Senozhatsky wrote:
> On (09/12/17 11:37), Minchan Kim wrote:
> > +		} else {
> > +			/* skip swapcache */
> > +			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
> 
> what if alloc_page_vma() fails?

Several modifications during development finally makes me remove the NULL check.
Thanks for catching it as well as style fix-up of other patch, Sergey.

From ac07fb0012bcd39c7a5bf5262c70c45d2e7df314 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Tue, 12 Sep 2017 08:44:29 +0900
Subject: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device

With fast swap storage, platform want to use swap more aggressively
and swap-in is crucial to application latency.

The rw_page based synchronous devices like zram, pmem and btt are such
fast storage. When I profile swapin performance with zram lz4 decompress
test, S/W overhead is more than 70%. Maybe, it would be bigger in nvdimm.

This patch aims for reducing swap-in latency via skipping swapcache
if swap device is synchronous device like rw_page based device.
It enhances 45% my swapin test(5G sequential swapin, no readahead,
from 2.41sec to 1.64sec).

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/swap.h |  1 +
 mm/memory.c          | 50 +++++++++++++++++++++++++++++++++++---------------
 mm/page_io.c         |  6 +++---
 mm/swapfile.c        | 11 +++++++----
 4 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 739d94397c47..fb46a3b55d65 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -462,6 +462,7 @@ extern int page_swapcount(struct page *);
 extern int __swp_swapcount(swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
 extern struct swap_info_struct *page_swap_info(struct page *);
+extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);
 extern bool reuse_swap_page(struct page *, int *);
 extern int try_to_free_swap(struct page *);
 struct backing_dev_info;
diff --git a/mm/memory.c b/mm/memory.c
index ec4e15494901..af1d7f2e9664 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2842,7 +2842,7 @@ EXPORT_SYMBOL(unmap_mapping_range);
 int do_swap_page(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
-	struct page *page = NULL, *swapcache;
+	struct page *page = NULL, *swapcache = NULL;
 	struct mem_cgroup *memcg;
 	struct vma_swap_readahead swap_ra;
 	swp_entry_t entry;
@@ -2881,17 +2881,35 @@ int do_swap_page(struct vm_fault *vmf)
 		}
 		goto out;
 	}
+
+
 	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
 	if (!page)
 		page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
 					 vmf->address);
 	if (!page) {
-		if (vma_readahead)
-			page = do_swap_page_readahead(entry,
-				GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
-		else
-			page = swapin_readahead(entry,
-				GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+		struct swap_info_struct *si = swp_swap_info(entry);
+
+		if (!(si->flags & SWP_SYNCHRONOUS_IO)) {
+			if (vma_readahead)
+				page = do_swap_page_readahead(entry,
+					GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
+			else
+				page = swapin_readahead(entry,
+					GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+			swapcache = page;
+		} else {
+			/* skip swapcache */
+			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+			if (page) {
+				__SetPageLocked(page);
+				__SetPageSwapBacked(page);
+				set_page_private(page, entry.val);
+				lru_cache_add_anon(page);
+				swap_readpage(page, true);
+			}
+		}
+
 		if (!page) {
 			/*
 			 * Back out if somebody else faulted in this pte
@@ -2920,7 +2938,6 @@ int do_swap_page(struct vm_fault *vmf)
 		goto out_release;
 	}
 
-	swapcache = page;
 	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
 
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
@@ -2935,7 +2952,8 @@ int do_swap_page(struct vm_fault *vmf)
 	 * test below, are not enough to exclude that.  Even if it is still
 	 * swapcache, we need to check that the page's swap has not changed.
 	 */
-	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
+	if (unlikely((!PageSwapCache(page) ||
+			page_private(page) != entry.val)) && swapcache)
 		goto out_page;
 
 	page = ksm_might_need_to_copy(page, vma, vmf->address);
@@ -2988,14 +3006,16 @@ int do_swap_page(struct vm_fault *vmf)
 		pte = pte_mksoft_dirty(pte);
 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
 	vmf->orig_pte = pte;
-	if (page == swapcache) {
-		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
-		mem_cgroup_commit_charge(page, memcg, true, false);
-		activate_page(page);
-	} else { /* ksm created a completely new copy */
+
+	/* ksm created a completely new copy */
+	if (unlikely(page != swapcache && swapcache)) {
 		page_add_new_anon_rmap(page, vma, vmf->address, false);
 		mem_cgroup_commit_charge(page, memcg, false, false);
 		lru_cache_add_active_or_unevictable(page, vma);
+	} else {
+		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
+		mem_cgroup_commit_charge(page, memcg, true, false);
+		activate_page(page);
 	}
 
 	swap_free(entry);
@@ -3003,7 +3023,7 @@ int do_swap_page(struct vm_fault *vmf)
 	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
 		try_to_free_swap(page);
 	unlock_page(page);
-	if (page != swapcache) {
+	if (page != swapcache && swapcache) {
 		/*
 		 * Hold the lock to avoid the swap entry to be reused
 		 * until we take the PT lock for the pte_same() check
diff --git a/mm/page_io.c b/mm/page_io.c
index 21502d341a67..d4a98e1f6608 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -346,7 +346,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 	return ret;
 }
 
-int swap_readpage(struct page *page, bool do_poll)
+int swap_readpage(struct page *page, bool synchronous)
 {
 	struct bio *bio;
 	int ret = 0;
@@ -354,7 +354,7 @@ int swap_readpage(struct page *page, bool do_poll)
 	blk_qc_t qc;
 	struct gendisk *disk;
 
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
+	VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageUptodate(page), page);
 	if (frontswap_load(page) == 0) {
@@ -402,7 +402,7 @@ int swap_readpage(struct page *page, bool do_poll)
 	count_vm_event(PSWPIN);
 	bio_get(bio);
 	qc = submit_bio(bio);
-	while (do_poll) {
+	while (synchronous) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		if (!READ_ONCE(bio->bi_private))
 			break;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1305591cde4d..64a3d85226ba 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3454,10 +3454,15 @@ int swapcache_prepare(swp_entry_t entry)
 	return __swap_duplicate(entry, SWAP_HAS_CACHE);
 }
 
+struct swap_info_struct *swp_swap_info(swp_entry_t entry)
+{
+	return swap_info[swp_type(entry)];
+}
+
 struct swap_info_struct *page_swap_info(struct page *page)
 {
-	swp_entry_t swap = { .val = page_private(page) };
-	return swap_info[swp_type(swap)];
+	swp_entry_t entry = { .val = page_private(page) };
+	return swp_swap_info(entry);
 }
 
 /*
@@ -3465,7 +3470,6 @@ struct swap_info_struct *page_swap_info(struct page *page)
  */
 struct address_space *__page_file_mapping(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return page_swap_info(page)->swap_file->f_mapping;
 }
 EXPORT_SYMBOL_GPL(__page_file_mapping);
@@ -3473,7 +3477,6 @@ EXPORT_SYMBOL_GPL(__page_file_mapping);
 pgoff_t __page_file_index(struct page *page)
 {
 	swp_entry_t swap = { .val = page_private(page) };
-	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return swp_offset(swap);
 }
 EXPORT_SYMBOL_GPL(__page_file_index);
-- 
2.7.4

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#1731306 — Re: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device

FromMinchan Kim <minchan@kernel.org>
Date2017-09-13 02:20 +0200
SubjectRe: [PATCH 5/5] mm:swap: skip swapcache for swapin of synchronous device
Message-ID<up3zk-8qb-13@gated-at.bofh.it>
In reply to#1730617
On Wed, Sep 13, 2017 at 04:22:59AM +0800, kbuild test robot wrote:
> Hi Minchan,
> 
> [auto build test ERROR on mmotm/master]
> [also build test ERROR on next-20170912]
> [cannot apply to linus/master v4.13]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Minchan-Kim/zram-set-BDI_CAP_STABLE_WRITES-once/20170913-025838
> base:   git://git.cmpxchg.org/linux-mmotm.git master
> config: x86_64-randconfig-x016-201737 (attached as .config)
> compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64 
> 
> All error/warnings (new ones prefixed by >>):

I will fix !CONFIG_SWAP.
Thanks, 0-day!

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#1730618 — [PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO

FromMinchan Kim <minchan@kernel.org>
Date2017-09-12 04:40 +0200
Subject[PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO
Message-ID<uoJhf-3C9-11@gated-at.bofh.it>
In reply to#1730616
If rw-page based fast storage is used for swap devices, we need to
detect it to enhance swap IO operations.
This patch is preparation for optimizing of swap-in operation with
next patch.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/swap.h | 3 ++-
 mm/swapfile.c        | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 8a807292037f..0f54b491e118 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -170,8 +170,9 @@ enum {
 	SWP_AREA_DISCARD = (1 << 8),	/* single-time swap area discards */
 	SWP_PAGE_DISCARD = (1 << 9),	/* freed swap page-cluster discards */
 	SWP_STABLE_WRITES = (1 << 10),	/* no overwrite PG_writeback pages */
+	SWP_SYNCHRONOUS_IO = (1<<11),	/* synchronous IO is efficient */
 					/* add others here before... */
-	SWP_SCANNING	= (1 << 11),	/* refcount in scan_swap_map */
+	SWP_SCANNING	= (1 << 12),	/* refcount in scan_swap_map */
 };
 
 #define SWAP_CLUSTER_MAX 32UL
diff --git a/mm/swapfile.c b/mm/swapfile.c
index bf91dc9e7a79..1305591cde4d 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3168,6 +3168,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
 		p->flags |= SWP_STABLE_WRITES;
 
+	if (bdi_cap_synchronous_io(inode_to_bdi(inode)))
+		p->flags |= SWP_SYNCHRONOUS_IO;
+
 	if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
 		int cpu;
 		unsigned long ci, nr_cluster;
-- 
2.7.4

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#1730651 — Re: [PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO

FromSergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Date2017-09-12 06:50 +0200
SubjectRe: [PATCH 3/5] mm:swap: introduce SWP_SYNCHRONOUS_IO
Message-ID<uoLj3-4YV-7@gated-at.bofh.it>
In reply to#1730618
On (09/12/17 11:37), Minchan Kim wrote:
[..]
> If rw-page based fast storage is used for swap devices, we need to
> detect it to enhance swap IO operations.
> This patch is preparation for optimizing of swap-in operation with
> next patch.
> 
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
>  include/linux/swap.h | 3 ++-
>  mm/swapfile.c        | 3 +++
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 8a807292037f..0f54b491e118 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -170,8 +170,9 @@ enum {
>  	SWP_AREA_DISCARD = (1 << 8),	/* single-time swap area discards */
>  	SWP_PAGE_DISCARD = (1 << 9),	/* freed swap page-cluster discards */
>  	SWP_STABLE_WRITES = (1 << 10),	/* no overwrite PG_writeback pages */
> +	SWP_SYNCHRONOUS_IO = (1<<11),	/* synchronous IO is efficient */
a nitpick:                  (1 << 11)

	-ss

>  					/* add others here before... */
> -	SWP_SCANNING	= (1 << 11),	/* refcount in scan_swap_map */
> +	SWP_SCANNING	= (1 << 12),	/* refcount in scan_swap_map */
>  };

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