[PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[Huang Ying]

After recent changes to the retrying and failure counting in
migrate_pages_batch(), it was found that it's unnecessary to count
retrying and failure for normal, large, and THP folios separately.
Because we don't use retrying and failure number of large folios
directly.  So, in this patch, we simplified retrying and failure
counting of large folios via counting retrying and failure of normal
and large folios together.  This results in the reduced line number.

This is just code cleanup, no functionality changes are expected.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Xin Hao <xhao@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
---
 mm/migrate.c | 103 +++++++++++++++++----------------------------------
 1 file changed, 35 insertions(+), 68 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 01cac26a3127..10709aed76d3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1614,11 +1614,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 		int nr_pass)
 {
 	int retry = 1;
-	int large_retry = 1;
 	int thp_retry = 1;
 	int nr_failed = 0;
 	int nr_retry_pages = 0;
-	int nr_large_failed = 0;
 	int pass = 0;
 	bool is_large = false;
 	bool is_thp = false;
@@ -1631,9 +1629,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
 			!list_empty(from) && !list_is_singular(from));
 
-	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
+	for (pass = 0; pass < nr_pass && retry; pass++) {
 		retry = 0;
-		large_retry = 0;
 		thp_retry = 0;
 		nr_retry_pages = 0;
 
@@ -1660,7 +1657,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 			 * list is processed.
 			 */
 			if (!thp_migration_supported() && is_thp) {
-				nr_large_failed++;
+				nr_failed++;
 				stats->nr_thp_failed++;
 				if (!try_split_folio(folio, split_folios)) {
 					stats->nr_thp_split++;
@@ -1688,38 +1685,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 				 * When memory is low, don't bother to try to migrate
 				 * other folios, move unmapped folios, then exit.
 				 */
-				if (is_large) {
-					nr_large_failed++;
-					stats->nr_thp_failed += is_thp;
-					/* Large folio NUMA faulting doesn't split to retry. */
-					if (!nosplit) {
-						int ret = try_split_folio(folio, split_folios);
-
-						if (!ret) {
-							stats->nr_thp_split += is_thp;
-							break;
-						} else if (reason == MR_LONGTERM_PIN &&
-							   ret == -EAGAIN) {
-							/*
-							 * Try again to split large folio to
-							 * mitigate the failure of longterm pinning.
-							 */
-							large_retry++;
-							thp_retry += is_thp;
-							nr_retry_pages += nr_pages;
-							/* Undo duplicated failure counting. */
-							nr_large_failed--;
-							stats->nr_thp_failed -= is_thp;
-							break;
-						}
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
+				/* Large folio NUMA faulting doesn't split to retry. */
+				if (is_large && !nosplit) {
+					int ret = try_split_folio(folio, split_folios);
+
+					if (!ret) {
+						stats->nr_thp_split += is_thp;
+						break;
+					} else if (reason == MR_LONGTERM_PIN &&
+						   ret == -EAGAIN) {
+						/*
+						 * Try again to split large folio to
+						 * mitigate the failure of longterm pinning.
+						 */
+						retry++;
+						thp_retry += is_thp;
+						nr_retry_pages += nr_pages;
+						/* Undo duplicated failure counting. */
+						nr_failed--;
+						stats->nr_thp_failed -= is_thp;
+						break;
 					}
-				} else {
-					nr_failed++;
 				}
 
 				stats->nr_failed_pages += nr_pages + nr_retry_pages;
 				/* nr_failed isn't updated for not used */
-				nr_large_failed += large_retry;
 				stats->nr_thp_failed += thp_retry;
 				rc_saved = rc;
 				if (list_empty(&unmap_folios))
@@ -1727,12 +1719,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 				else
 					goto move;
 			case -EAGAIN:
-				if (is_large) {
-					large_retry++;
-					thp_retry += is_thp;
-				} else {
-					retry++;
-				}
+				retry++;
+				thp_retry += is_thp;
 				nr_retry_pages += nr_pages;
 				break;
 			case MIGRATEPAGE_SUCCESS:
@@ -1750,20 +1738,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 				 * removed from migration folio list and not
 				 * retried in the next outer loop.
 				 */
-				if (is_large) {
-					nr_large_failed++;
-					stats->nr_thp_failed += is_thp;
-				} else {
-					nr_failed++;
-				}
-
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
 				stats->nr_failed_pages += nr_pages;
 				break;
 			}
 		}
 	}
 	nr_failed += retry;
-	nr_large_failed += large_retry;
 	stats->nr_thp_failed += thp_retry;
 	stats->nr_failed_pages += nr_retry_pages;
 move:
@@ -1771,17 +1753,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 	try_to_unmap_flush();
 
 	retry = 1;
-	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
+	for (pass = 0; pass < nr_pass && retry; pass++) {
 		retry = 0;
-		large_retry = 0;
 		thp_retry = 0;
 		nr_retry_pages = 0;
 
 		dst = list_first_entry(&dst_folios, struct folio, lru);
 		dst2 = list_next_entry(dst, lru);
 		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
-			is_large = folio_test_large(folio);
-			is_thp = is_large && folio_test_pmd_mappable(folio);
+			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
 			nr_pages = folio_nr_pages(folio);
 
 			cond_resched();
@@ -1797,12 +1777,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 			 */
 			switch(rc) {
 			case -EAGAIN:
-				if (is_large) {
-					large_retry++;
-					thp_retry += is_thp;
-				} else {
-					retry++;
-				}
+				retry++;
+				thp_retry += is_thp;
 				nr_retry_pages += nr_pages;
 				break;
 			case MIGRATEPAGE_SUCCESS:
@@ -1810,13 +1786,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 				stats->nr_thp_succeeded += is_thp;
 				break;
 			default:
-				if (is_large) {
-					nr_large_failed++;
-					stats->nr_thp_failed += is_thp;
-				} else {
-					nr_failed++;
-				}
-
+				nr_failed++;
+				stats->nr_thp_failed += is_thp;
 				stats->nr_failed_pages += nr_pages;
 				break;
 			}
@@ -1825,14 +1796,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 		}
 	}
 	nr_failed += retry;
-	nr_large_failed += large_retry;
 	stats->nr_thp_failed += thp_retry;
 	stats->nr_failed_pages += nr_retry_pages;
 
-	if (rc_saved)
-		rc = rc_saved;
-	else
-		rc = nr_failed + nr_large_failed;
+	rc = rc_saved ? : nr_failed;
 out:
 	/* Cleanup remaining folios */
 	dst = list_first_entry(&dst_folios, struct folio, lru);
-- 
2.39.2

[PATCH 2/2] migrate_pages_batch: code cleanup: remove is_large

[Huang Ying]

Previously, in migrate_pages_batch we need to track whether the source
folio is large/THP before splitting.  So is_large is used to cache
folio_test_large() result.  Now, we don't need that variable any more
because we don't count retrying and failure of large folios (only
counting that of THP folios).  So, in this patch, is_large is removed
to simplify the code.

This is just code cleanup, no functionality changes are expected.

Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Xin Hao <xhao@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
---
 mm/migrate.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 10709aed76d3..2ac927a82bbc 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1618,7 +1618,6 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 	int nr_failed = 0;
 	int nr_retry_pages = 0;
 	int pass = 0;
-	bool is_large = false;
 	bool is_thp = false;
 	struct folio *folio, *folio2, *dst = NULL, *dst2;
 	int rc, rc_saved = 0, nr_pages;
@@ -1635,13 +1634,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 		nr_retry_pages = 0;
 
 		list_for_each_entry_safe(folio, folio2, from, lru) {
-			/*
-			 * Large folio statistics is based on the source large
-			 * folio. Capture required information that might get
-			 * lost during migration.
-			 */
-			is_large = folio_test_large(folio);
-			is_thp = is_large && folio_test_pmd_mappable(folio);
+			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
 			nr_pages = folio_nr_pages(folio);
 
 			cond_resched();
@@ -1688,7 +1681,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
 				nr_failed++;
 				stats->nr_thp_failed += is_thp;
 				/* Large folio NUMA faulting doesn't split to retry. */
-				if (is_large && !nosplit) {
+				if (folio_test_large(folio) && !nosplit) {
 					int ret = try_split_folio(folio, split_folios);
 
 					if (!ret) {
-- 
2.39.2

Re: [PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[Alistair Popple]

Huang Ying <ying.huang@intel.com> writes:

> After recent changes to the retrying and failure counting in
> migrate_pages_batch(), it was found that it's unnecessary to count
> retrying and failure for normal, large, and THP folios separately.
> Because we don't use retrying and failure number of large folios
> directly.  So, in this patch, we simplified retrying and failure
> counting of large folios via counting retrying and failure of normal
> and large folios together.  This results in the reduced line number.
>
> This is just code cleanup, no functionality changes are expected.

Quite a nice cleanup, thanks. Feel free to add:

Reviewed-by: Alistair Popple <apopple@nvidia.com>

> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/migrate.c | 103 +++++++++++++++++----------------------------------
>  1 file changed, 35 insertions(+), 68 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 01cac26a3127..10709aed76d3 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1614,11 +1614,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  		int nr_pass)
>  {
>  	int retry = 1;
> -	int large_retry = 1;
>  	int thp_retry = 1;
>  	int nr_failed = 0;
>  	int nr_retry_pages = 0;
> -	int nr_large_failed = 0;
>  	int pass = 0;
>  	bool is_large = false;
>  	bool is_thp = false;
> @@ -1631,9 +1629,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
>  			!list_empty(from) && !list_is_singular(from));
>  
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>  		retry = 0;
> -		large_retry = 0;
>  		thp_retry = 0;
>  		nr_retry_pages = 0;
>  
> @@ -1660,7 +1657,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  			 * list is processed.
>  			 */
>  			if (!thp_migration_supported() && is_thp) {
> -				nr_large_failed++;
> +				nr_failed++;
>  				stats->nr_thp_failed++;
>  				if (!try_split_folio(folio, split_folios)) {
>  					stats->nr_thp_split++;
> @@ -1688,38 +1685,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				 * When memory is low, don't bother to try to migrate
>  				 * other folios, move unmapped folios, then exit.
>  				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -					/* Large folio NUMA faulting doesn't split to retry. */
> -					if (!nosplit) {
> -						int ret = try_split_folio(folio, split_folios);
> -
> -						if (!ret) {
> -							stats->nr_thp_split += is_thp;
> -							break;
> -						} else if (reason == MR_LONGTERM_PIN &&
> -							   ret == -EAGAIN) {
> -							/*
> -							 * Try again to split large folio to
> -							 * mitigate the failure of longterm pinning.
> -							 */
> -							large_retry++;
> -							thp_retry += is_thp;
> -							nr_retry_pages += nr_pages;
> -							/* Undo duplicated failure counting. */
> -							nr_large_failed--;
> -							stats->nr_thp_failed -= is_thp;
> -							break;
> -						}
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
> +				/* Large folio NUMA faulting doesn't split to retry. */
> +				if (is_large && !nosplit) {
> +					int ret = try_split_folio(folio, split_folios);
> +
> +					if (!ret) {
> +						stats->nr_thp_split += is_thp;
> +						break;
> +					} else if (reason == MR_LONGTERM_PIN &&
> +						   ret == -EAGAIN) {
> +						/*
> +						 * Try again to split large folio to
> +						 * mitigate the failure of longterm pinning.
> +						 */
> +						retry++;
> +						thp_retry += is_thp;
> +						nr_retry_pages += nr_pages;
> +						/* Undo duplicated failure counting. */
> +						nr_failed--;
> +						stats->nr_thp_failed -= is_thp;
> +						break;
>  					}
> -				} else {
> -					nr_failed++;
>  				}
>  
>  				stats->nr_failed_pages += nr_pages + nr_retry_pages;
>  				/* nr_failed isn't updated for not used */
> -				nr_large_failed += large_retry;
>  				stats->nr_thp_failed += thp_retry;
>  				rc_saved = rc;
>  				if (list_empty(&unmap_folios))
> @@ -1727,12 +1719,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				else
>  					goto move;
>  			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>  				nr_retry_pages += nr_pages;
>  				break;
>  			case MIGRATEPAGE_SUCCESS:
> @@ -1750,20 +1738,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				 * removed from migration folio list and not
>  				 * retried in the next outer loop.
>  				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>  				stats->nr_failed_pages += nr_pages;
>  				break;
>  			}
>  		}
>  	}
>  	nr_failed += retry;
> -	nr_large_failed += large_retry;
>  	stats->nr_thp_failed += thp_retry;
>  	stats->nr_failed_pages += nr_retry_pages;
>  move:
> @@ -1771,17 +1753,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  	try_to_unmap_flush();
>  
>  	retry = 1;
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>  		retry = 0;
> -		large_retry = 0;
>  		thp_retry = 0;
>  		nr_retry_pages = 0;
>  
>  		dst = list_first_entry(&dst_folios, struct folio, lru);
>  		dst2 = list_next_entry(dst, lru);
>  		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
> -			is_large = folio_test_large(folio);
> -			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>  			nr_pages = folio_nr_pages(folio);
>  
>  			cond_resched();
> @@ -1797,12 +1777,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  			 */
>  			switch(rc) {
>  			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>  				nr_retry_pages += nr_pages;
>  				break;
>  			case MIGRATEPAGE_SUCCESS:
> @@ -1810,13 +1786,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				stats->nr_thp_succeeded += is_thp;
>  				break;
>  			default:
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>  				stats->nr_failed_pages += nr_pages;
>  				break;
>  			}
> @@ -1825,14 +1796,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  		}
>  	}
>  	nr_failed += retry;
> -	nr_large_failed += large_retry;
>  	stats->nr_thp_failed += thp_retry;
>  	stats->nr_failed_pages += nr_retry_pages;
>  
> -	if (rc_saved)
> -		rc = rc_saved;
> -	else
> -		rc = nr_failed + nr_large_failed;
> +	rc = rc_saved ? : nr_failed;
>  out:
>  	/* Cleanup remaining folios */
>  	dst = list_first_entry(&dst_folios, struct folio, lru);

Re: [PATCH 2/2] migrate_pages_batch: code cleanup: remove is_large

[Alistair Popple]

Huang Ying <ying.huang@intel.com> writes:

> Previously, in migrate_pages_batch we need to track whether the source
> folio is large/THP before splitting.  So is_large is used to cache
> folio_test_large() result.  Now, we don't need that variable any more
> because we don't count retrying and failure of large folios (only
> counting that of THP folios).  So, in this patch, is_large is removed
> to simplify the code.
>
> This is just code cleanup, no functionality changes are expected.

Reviewed-by: Alistair Popple <apopple@nvidia.com>

> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/migrate.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 10709aed76d3..2ac927a82bbc 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1618,7 +1618,6 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  	int nr_failed = 0;
>  	int nr_retry_pages = 0;
>  	int pass = 0;
> -	bool is_large = false;
>  	bool is_thp = false;
>  	struct folio *folio, *folio2, *dst = NULL, *dst2;
>  	int rc, rc_saved = 0, nr_pages;
> @@ -1635,13 +1634,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  		nr_retry_pages = 0;
>  
>  		list_for_each_entry_safe(folio, folio2, from, lru) {
> -			/*
> -			 * Large folio statistics is based on the source large
> -			 * folio. Capture required information that might get
> -			 * lost during migration.
> -			 */
> -			is_large = folio_test_large(folio);
> -			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>  			nr_pages = folio_nr_pages(folio);
>  
>  			cond_resched();
> @@ -1688,7 +1681,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				nr_failed++;
>  				stats->nr_thp_failed += is_thp;
>  				/* Large folio NUMA faulting doesn't split to retry. */
> -				if (is_large && !nosplit) {
> +				if (folio_test_large(folio) && !nosplit) {
>  					int ret = try_split_folio(folio, split_folios);
>  
>  					if (!ret) {

Re: [PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[Zi Yan]

[-- Attachment #1: Type: text/plain, Size: 7812 bytes --]

On 8 May 2023, at 22:20, Huang Ying wrote:

> After recent changes to the retrying and failure counting in
> migrate_pages_batch(), it was found that it's unnecessary to count
> retrying and failure for normal, large, and THP folios separately.
> Because we don't use retrying and failure number of large folios
> directly.  So, in this patch, we simplified retrying and failure
> counting of large folios via counting retrying and failure of normal
> and large folios together.  This results in the reduced line number.
>
> This is just code cleanup, no functionality changes are expected.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/migrate.c | 103 +++++++++++++++++----------------------------------
>  1 file changed, 35 insertions(+), 68 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 01cac26a3127..10709aed76d3 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1614,11 +1614,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  		int nr_pass)
>  {
>  	int retry = 1;
> -	int large_retry = 1;
>  	int thp_retry = 1;
>  	int nr_failed = 0;
>  	int nr_retry_pages = 0;
> -	int nr_large_failed = 0;
>  	int pass = 0;
>  	bool is_large = false;
>  	bool is_thp = false;
> @@ -1631,9 +1629,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
>  			!list_empty(from) && !list_is_singular(from));
>
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>  		retry = 0;
> -		large_retry = 0;
>  		thp_retry = 0;
>  		nr_retry_pages = 0;
>
> @@ -1660,7 +1657,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  			 * list is processed.
>  			 */
>  			if (!thp_migration_supported() && is_thp) {
> -				nr_large_failed++;
> +				nr_failed++;
>  				stats->nr_thp_failed++;
>  				if (!try_split_folio(folio, split_folios)) {
>  					stats->nr_thp_split++;
> @@ -1688,38 +1685,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				 * When memory is low, don't bother to try to migrate
>  				 * other folios, move unmapped folios, then exit.
>  				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -					/* Large folio NUMA faulting doesn't split to retry. */
> -					if (!nosplit) {
> -						int ret = try_split_folio(folio, split_folios);
> -
> -						if (!ret) {
> -							stats->nr_thp_split += is_thp;
> -							break;
> -						} else if (reason == MR_LONGTERM_PIN &&
> -							   ret == -EAGAIN) {
> -							/*
> -							 * Try again to split large folio to
> -							 * mitigate the failure of longterm pinning.
> -							 */
> -							large_retry++;
> -							thp_retry += is_thp;
> -							nr_retry_pages += nr_pages;
> -							/* Undo duplicated failure counting. */
> -							nr_large_failed--;
> -							stats->nr_thp_failed -= is_thp;
> -							break;
> -						}
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
> +				/* Large folio NUMA faulting doesn't split to retry. */
> +				if (is_large && !nosplit) {
> +					int ret = try_split_folio(folio, split_folios);
> +
> +					if (!ret) {
> +						stats->nr_thp_split += is_thp;
> +						break;
> +					} else if (reason == MR_LONGTERM_PIN &&
> +						   ret == -EAGAIN) {
> +						/*
> +						 * Try again to split large folio to
> +						 * mitigate the failure of longterm pinning.
> +						 */
> +						retry++;
> +						thp_retry += is_thp;
> +						nr_retry_pages += nr_pages;
> +						/* Undo duplicated failure counting. */
> +						nr_failed--;
> +						stats->nr_thp_failed -= is_thp;
> +						break;
>  					}
> -				} else {
> -					nr_failed++;
>  				}
>
>  				stats->nr_failed_pages += nr_pages + nr_retry_pages;
>  				/* nr_failed isn't updated for not used */
> -				nr_large_failed += large_retry;
>  				stats->nr_thp_failed += thp_retry;
>  				rc_saved = rc;
>  				if (list_empty(&unmap_folios))
> @@ -1727,12 +1719,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				else
>  					goto move;
>  			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>  				nr_retry_pages += nr_pages;
>  				break;
>  			case MIGRATEPAGE_SUCCESS:
> @@ -1750,20 +1738,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				 * removed from migration folio list and not
>  				 * retried in the next outer loop.
>  				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>  				stats->nr_failed_pages += nr_pages;
>  				break;
>  			}
>  		}
>  	}
>  	nr_failed += retry;
> -	nr_large_failed += large_retry;
>  	stats->nr_thp_failed += thp_retry;
>  	stats->nr_failed_pages += nr_retry_pages;
>  move:
> @@ -1771,17 +1753,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  	try_to_unmap_flush();
>
>  	retry = 1;
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>  		retry = 0;
> -		large_retry = 0;
>  		thp_retry = 0;
>  		nr_retry_pages = 0;
>
>  		dst = list_first_entry(&dst_folios, struct folio, lru);
>  		dst2 = list_next_entry(dst, lru);
>  		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
> -			is_large = folio_test_large(folio);
> -			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);

Should this be part of patch 2? Or maybe just merge two patches?

>  			nr_pages = folio_nr_pages(folio);
>
>  			cond_resched();
> @@ -1797,12 +1777,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  			 */
>  			switch(rc) {
>  			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>  				nr_retry_pages += nr_pages;
>  				break;
>  			case MIGRATEPAGE_SUCCESS:
> @@ -1810,13 +1786,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  				stats->nr_thp_succeeded += is_thp;
>  				break;
>  			default:
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>  				stats->nr_failed_pages += nr_pages;
>  				break;
>  			}
> @@ -1825,14 +1796,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>  		}
>  	}
>  	nr_failed += retry;
> -	nr_large_failed += large_retry;
>  	stats->nr_thp_failed += thp_retry;
>  	stats->nr_failed_pages += nr_retry_pages;
>
> -	if (rc_saved)
> -		rc = rc_saved;
> -	else
> -		rc = nr_failed + nr_large_failed;
> +	rc = rc_saved ? : nr_failed;
>  out:
>  	/* Cleanup remaining folios */
>  	dst = list_first_entry(&dst_folios, struct folio, lru);
> -- 
> 2.39.2

Otherwise LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>


--
Best Regards,
Yan, Zi

[-- Attachment #2: OpenPGP digital signature --]
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Re: [PATCH 2/2] migrate_pages_batch: code cleanup: remove is_large

[Zi Yan]

[-- Attachment #1: Type: text/plain, Size: 951 bytes --]

On 8 May 2023, at 22:20, Huang Ying wrote:

> Previously, in migrate_pages_batch we need to track whether the source
> folio is large/THP before splitting.  So is_large is used to cache
> folio_test_large() result.  Now, we don't need that variable any more
> because we don't count retrying and failure of large folios (only
> counting that of THP folios).  So, in this patch, is_large is removed
> to simplify the code.
>
> This is just code cleanup, no functionality changes are expected.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>  mm/migrate.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>


LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>

--
Best Regards,
Yan, Zi

[-- Attachment #2: OpenPGP digital signature --]
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Re: [PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[haoxin]

在 2023/5/9 上午10:20, Huang Ying 写道:
> After recent changes to the retrying and failure counting in
> migrate_pages_batch(), it was found that it's unnecessary to count
> retrying and failure for normal, large, and THP folios separately.
> Because we don't use retrying and failure number of large folios
> directly.  So, in this patch, we simplified retrying and failure
> counting of large folios via counting retrying and failure of normal
> and large folios together.  This results in the reduced line number.
>
> This is just code cleanup, no functionality changes are expected.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>   mm/migrate.c | 103 +++++++++++++++++----------------------------------
>   1 file changed, 35 insertions(+), 68 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 01cac26a3127..10709aed76d3 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1614,11 +1614,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   		int nr_pass)
>   {
>   	int retry = 1;
> -	int large_retry = 1;
>   	int thp_retry = 1;
>   	int nr_failed = 0;
>   	int nr_retry_pages = 0;
> -	int nr_large_failed = 0;
>   	int pass = 0;
>   	bool is_large = false;
>   	bool is_thp = false;
> @@ -1631,9 +1629,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
>   			!list_empty(from) && !list_is_singular(from));
>   
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>   		retry = 0;
> -		large_retry = 0;
>   		thp_retry = 0;
>   		nr_retry_pages = 0;
>   
> @@ -1660,7 +1657,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   			 * list is processed.
>   			 */
>   			if (!thp_migration_supported() && is_thp) {
> -				nr_large_failed++;
> +				nr_failed++;
>   				stats->nr_thp_failed++;
>   				if (!try_split_folio(folio, split_folios)) {
>   					stats->nr_thp_split++;
> @@ -1688,38 +1685,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   				 * When memory is low, don't bother to try to migrate
>   				 * other folios, move unmapped folios, then exit.
>   				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -					/* Large folio NUMA faulting doesn't split to retry. */
> -					if (!nosplit) {
> -						int ret = try_split_folio(folio, split_folios);
> -
> -						if (!ret) {
> -							stats->nr_thp_split += is_thp;
> -							break;
> -						} else if (reason == MR_LONGTERM_PIN &&
> -							   ret == -EAGAIN) {
> -							/*
> -							 * Try again to split large folio to
> -							 * mitigate the failure of longterm pinning.
> -							 */
> -							large_retry++;
> -							thp_retry += is_thp;
> -							nr_retry_pages += nr_pages;
> -							/* Undo duplicated failure counting. */
> -							nr_large_failed--;
> -							stats->nr_thp_failed -= is_thp;
> -							break;
> -						}
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
> +				/* Large folio NUMA faulting doesn't split to retry. */
> +				if (is_large && !nosplit) {
> +					int ret = try_split_folio(folio, split_folios);
> +
> +					if (!ret) {
> +						stats->nr_thp_split += is_thp;
> +						break;
> +					} else if (reason == MR_LONGTERM_PIN &&
> +						   ret == -EAGAIN) {
> +						/*
> +						 * Try again to split large folio to
> +						 * mitigate the failure of longterm pinning.
> +						 */
> +						retry++;
> +						thp_retry += is_thp;
> +						nr_retry_pages += nr_pages;
> +						/* Undo duplicated failure counting. */
> +						nr_failed--;
> +						stats->nr_thp_failed -= is_thp;
> +						break;
>   					}
> -				} else {
> -					nr_failed++;
>   				}
>   
>   				stats->nr_failed_pages += nr_pages + nr_retry_pages;
>   				/* nr_failed isn't updated for not used */
> -				nr_large_failed += large_retry;
>   				stats->nr_thp_failed += thp_retry;
>   				rc_saved = rc;
>   				if (list_empty(&unmap_folios))
> @@ -1727,12 +1719,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   				else
>   					goto move;
>   			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>   				nr_retry_pages += nr_pages;
>   				break;
>   			case MIGRATEPAGE_SUCCESS:
> @@ -1750,20 +1738,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   				 * removed from migration folio list and not
>   				 * retried in the next outer loop.
>   				 */
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>   				stats->nr_failed_pages += nr_pages;
>   				break;
>   			}
>   		}
>   	}
>   	nr_failed += retry;
> -	nr_large_failed += large_retry;
>   	stats->nr_thp_failed += thp_retry;
>   	stats->nr_failed_pages += nr_retry_pages;
>   move:
> @@ -1771,17 +1753,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   	try_to_unmap_flush();
>   
>   	retry = 1;
> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>   		retry = 0;
> -		large_retry = 0;
>   		thp_retry = 0;
>   		nr_retry_pages = 0;
>   
>   		dst = list_first_entry(&dst_folios, struct folio, lru);
>   		dst2 = list_next_entry(dst, lru);
>   		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
> -			is_large = folio_test_large(folio);
> -			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>   			nr_pages = folio_nr_pages(folio);
>   
>   			cond_resched();
> @@ -1797,12 +1777,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   			 */
>   			switch(rc) {
>   			case -EAGAIN:
> -				if (is_large) {
> -					large_retry++;
> -					thp_retry += is_thp;
> -				} else {
> -					retry++;
> -				}
> +				retry++;
> +				thp_retry += is_thp;
>   				nr_retry_pages += nr_pages;
>   				break;
>   			case MIGRATEPAGE_SUCCESS:
> @@ -1810,13 +1786,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   				stats->nr_thp_succeeded += is_thp;
>   				break;
>   			default:
> -				if (is_large) {
> -					nr_large_failed++;
> -					stats->nr_thp_failed += is_thp;
> -				} else {
> -					nr_failed++;
> -				}
> -
> +				nr_failed++;
> +				stats->nr_thp_failed += is_thp;
>   				stats->nr_failed_pages += nr_pages;
>   				break;
>   			}
> @@ -1825,14 +1796,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   		}
>   	}
>   	nr_failed += retry;
> -	nr_large_failed += large_retry;
>   	stats->nr_thp_failed += thp_retry;
>   	stats->nr_failed_pages += nr_retry_pages;
>   
> -	if (rc_saved)
> -		rc = rc_saved;
> -	else
> -		rc = nr_failed + nr_large_failed;
> +	rc = rc_saved ? : nr_failed;
>   out:
>   	/* Cleanup remaining folios */
>   	dst = list_first_entry(&dst_folios, struct folio, lru);

LGTM.

Reviewed-by: Xin Hao <xhao@linux.alibaba.com>

Re: [PATCH 2/2] migrate_pages_batch: code cleanup: remove is_large

[haoxin]

在 2023/5/9 上午10:20, Huang Ying 写道:
> Previously, in migrate_pages_batch we need to track whether the source
> folio is large/THP before splitting.  So is_large is used to cache
> folio_test_large() result.  Now, we don't need that variable any more
> because we don't count retrying and failure of large folios (only
> counting that of THP folios).  So, in this patch, is_large is removed
> to simplify the code.
>
> This is just code cleanup, no functionality changes are expected.
>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Xin Hao <xhao@linux.alibaba.com>
> Cc: Zi Yan <ziy@nvidia.com>
> Cc: Yang Shi <shy828301@gmail.com>
> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> ---
>   mm/migrate.c | 11 ++---------
>   1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 10709aed76d3..2ac927a82bbc 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1618,7 +1618,6 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   	int nr_failed = 0;
>   	int nr_retry_pages = 0;
>   	int pass = 0;
> -	bool is_large = false;
>   	bool is_thp = false;
>   	struct folio *folio, *folio2, *dst = NULL, *dst2;
>   	int rc, rc_saved = 0, nr_pages;
> @@ -1635,13 +1634,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   		nr_retry_pages = 0;
>   
>   		list_for_each_entry_safe(folio, folio2, from, lru) {
> -			/*
> -			 * Large folio statistics is based on the source large
> -			 * folio. Capture required information that might get
> -			 * lost during migration.
> -			 */
> -			is_large = folio_test_large(folio);
> -			is_thp = is_large && folio_test_pmd_mappable(folio);
> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>   			nr_pages = folio_nr_pages(folio);
>   
>   			cond_resched();
> @@ -1688,7 +1681,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>   				nr_failed++;
>   				stats->nr_thp_failed += is_thp;
>   				/* Large folio NUMA faulting doesn't split to retry. */
> -				if (is_large && !nosplit) {
> +				if (folio_test_large(folio) && !nosplit) {
>   					int ret = try_split_folio(folio, split_folios);
>   
>   					if (!ret) {
LGTM.
Reviewed-by: Xin Hao <xhao@linux.alibaba.com>

Re: [PATCH 1/2] migrate_pages_batch: simplify retrying and failure counting of large folios

[Huang, Ying]

Zi Yan <ziy@nvidia.com> writes:

> On 8 May 2023, at 22:20, Huang Ying wrote:
>
>> After recent changes to the retrying and failure counting in
>> migrate_pages_batch(), it was found that it's unnecessary to count
>> retrying and failure for normal, large, and THP folios separately.
>> Because we don't use retrying and failure number of large folios
>> directly.  So, in this patch, we simplified retrying and failure
>> counting of large folios via counting retrying and failure of normal
>> and large folios together.  This results in the reduced line number.
>>
>> This is just code cleanup, no functionality changes are expected.
>>
>> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
>> Cc: Xin Hao <xhao@linux.alibaba.com>
>> Cc: Zi Yan <ziy@nvidia.com>
>> Cc: Yang Shi <shy828301@gmail.com>
>> Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
>> Cc: Oscar Salvador <osalvador@suse.de>
>> Cc: Alistair Popple <apopple@nvidia.com>
>> ---
>>  mm/migrate.c | 103 +++++++++++++++++----------------------------------
>>  1 file changed, 35 insertions(+), 68 deletions(-)
>>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 01cac26a3127..10709aed76d3 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1614,11 +1614,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  		int nr_pass)
>>  {
>>  	int retry = 1;
>> -	int large_retry = 1;
>>  	int thp_retry = 1;
>>  	int nr_failed = 0;
>>  	int nr_retry_pages = 0;
>> -	int nr_large_failed = 0;
>>  	int pass = 0;
>>  	bool is_large = false;
>>  	bool is_thp = false;
>> @@ -1631,9 +1629,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  	VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
>>  			!list_empty(from) && !list_is_singular(from));
>>
>> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
>> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>>  		retry = 0;
>> -		large_retry = 0;
>>  		thp_retry = 0;
>>  		nr_retry_pages = 0;
>>
>> @@ -1660,7 +1657,7 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  			 * list is processed.
>>  			 */
>>  			if (!thp_migration_supported() && is_thp) {
>> -				nr_large_failed++;
>> +				nr_failed++;
>>  				stats->nr_thp_failed++;
>>  				if (!try_split_folio(folio, split_folios)) {
>>  					stats->nr_thp_split++;
>> @@ -1688,38 +1685,33 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  				 * When memory is low, don't bother to try to migrate
>>  				 * other folios, move unmapped folios, then exit.
>>  				 */
>> -				if (is_large) {
>> -					nr_large_failed++;
>> -					stats->nr_thp_failed += is_thp;
>> -					/* Large folio NUMA faulting doesn't split to retry. */
>> -					if (!nosplit) {
>> -						int ret = try_split_folio(folio, split_folios);
>> -
>> -						if (!ret) {
>> -							stats->nr_thp_split += is_thp;
>> -							break;
>> -						} else if (reason == MR_LONGTERM_PIN &&
>> -							   ret == -EAGAIN) {
>> -							/*
>> -							 * Try again to split large folio to
>> -							 * mitigate the failure of longterm pinning.
>> -							 */
>> -							large_retry++;
>> -							thp_retry += is_thp;
>> -							nr_retry_pages += nr_pages;
>> -							/* Undo duplicated failure counting. */
>> -							nr_large_failed--;
>> -							stats->nr_thp_failed -= is_thp;
>> -							break;
>> -						}
>> +				nr_failed++;
>> +				stats->nr_thp_failed += is_thp;
>> +				/* Large folio NUMA faulting doesn't split to retry. */
>> +				if (is_large && !nosplit) {
>> +					int ret = try_split_folio(folio, split_folios);
>> +
>> +					if (!ret) {
>> +						stats->nr_thp_split += is_thp;
>> +						break;
>> +					} else if (reason == MR_LONGTERM_PIN &&
>> +						   ret == -EAGAIN) {
>> +						/*
>> +						 * Try again to split large folio to
>> +						 * mitigate the failure of longterm pinning.
>> +						 */
>> +						retry++;
>> +						thp_retry += is_thp;
>> +						nr_retry_pages += nr_pages;
>> +						/* Undo duplicated failure counting. */
>> +						nr_failed--;
>> +						stats->nr_thp_failed -= is_thp;
>> +						break;
>>  					}
>> -				} else {
>> -					nr_failed++;
>>  				}
>>
>>  				stats->nr_failed_pages += nr_pages + nr_retry_pages;
>>  				/* nr_failed isn't updated for not used */
>> -				nr_large_failed += large_retry;
>>  				stats->nr_thp_failed += thp_retry;
>>  				rc_saved = rc;
>>  				if (list_empty(&unmap_folios))
>> @@ -1727,12 +1719,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  				else
>>  					goto move;
>>  			case -EAGAIN:
>> -				if (is_large) {
>> -					large_retry++;
>> -					thp_retry += is_thp;
>> -				} else {
>> -					retry++;
>> -				}
>> +				retry++;
>> +				thp_retry += is_thp;
>>  				nr_retry_pages += nr_pages;
>>  				break;
>>  			case MIGRATEPAGE_SUCCESS:
>> @@ -1750,20 +1738,14 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  				 * removed from migration folio list and not
>>  				 * retried in the next outer loop.
>>  				 */
>> -				if (is_large) {
>> -					nr_large_failed++;
>> -					stats->nr_thp_failed += is_thp;
>> -				} else {
>> -					nr_failed++;
>> -				}
>> -
>> +				nr_failed++;
>> +				stats->nr_thp_failed += is_thp;
>>  				stats->nr_failed_pages += nr_pages;
>>  				break;
>>  			}
>>  		}
>>  	}
>>  	nr_failed += retry;
>> -	nr_large_failed += large_retry;
>>  	stats->nr_thp_failed += thp_retry;
>>  	stats->nr_failed_pages += nr_retry_pages;
>>  move:
>> @@ -1771,17 +1753,15 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  	try_to_unmap_flush();
>>
>>  	retry = 1;
>> -	for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
>> +	for (pass = 0; pass < nr_pass && retry; pass++) {
>>  		retry = 0;
>> -		large_retry = 0;
>>  		thp_retry = 0;
>>  		nr_retry_pages = 0;
>>
>>  		dst = list_first_entry(&dst_folios, struct folio, lru);
>>  		dst2 = list_next_entry(dst, lru);
>>  		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
>> -			is_large = folio_test_large(folio);
>> -			is_thp = is_large && folio_test_pmd_mappable(folio);
>> +			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
>
> Should this be part of patch 2? Or maybe just merge two patches?

OK.  Will merge 2 patches.

>>  			nr_pages = folio_nr_pages(folio);
>>
>>  			cond_resched();
>> @@ -1797,12 +1777,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  			 */
>>  			switch(rc) {
>>  			case -EAGAIN:
>> -				if (is_large) {
>> -					large_retry++;
>> -					thp_retry += is_thp;
>> -				} else {
>> -					retry++;
>> -				}
>> +				retry++;
>> +				thp_retry += is_thp;
>>  				nr_retry_pages += nr_pages;
>>  				break;
>>  			case MIGRATEPAGE_SUCCESS:
>> @@ -1810,13 +1786,8 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  				stats->nr_thp_succeeded += is_thp;
>>  				break;
>>  			default:
>> -				if (is_large) {
>> -					nr_large_failed++;
>> -					stats->nr_thp_failed += is_thp;
>> -				} else {
>> -					nr_failed++;
>> -				}
>> -
>> +				nr_failed++;
>> +				stats->nr_thp_failed += is_thp;
>>  				stats->nr_failed_pages += nr_pages;
>>  				break;
>>  			}
>> @@ -1825,14 +1796,10 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
>>  		}
>>  	}
>>  	nr_failed += retry;
>> -	nr_large_failed += large_retry;
>>  	stats->nr_thp_failed += thp_retry;
>>  	stats->nr_failed_pages += nr_retry_pages;
>>
>> -	if (rc_saved)
>> -		rc = rc_saved;
>> -	else
>> -		rc = nr_failed + nr_large_failed;
>> +	rc = rc_saved ? : nr_failed;
>>  out:
>>  	/* Cleanup remaining folios */
>>  	dst = list_first_entry(&dst_folios, struct folio, lru);
>> -- 
>> 2.39.2
>
> Otherwise LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>

Thanks!

Best Regards,
Huang, Ying