Subject: Re: linux-next: manual merge of the akpm-current tree with the hmm tree

From: Andrew Morton <[email-masked]>
Date: Sat, 6 Jul 2019 22:04:26 -0700

On Fri, 5 Jul 2019 12:08:15 +0000 Jason Gunthorpe <[email-masked]> wrote:

> On Thu, Jul 04, 2019 at 04:29:55PM -0700, Dan Williams wrote:
> > Guys, Andrew has kicked the subsection patches out of -mm because of
> > the merge conflicts. Can we hold off on the hmm cleanups for this
> > cycle?
> 
> I agree with you we should prioritize your subsection patches over
> CH's cleanup if we cannot have both.
> 
> As I said, I'll drop CH's at Andrews request, but I do not want to
> make any changes without being aligned with him.

OK, I had a shot at repairing the damage on top of current linux-next. 
The great majority of the issues were in
mm-devm_memremap_pages-enable-sub-section-remap.patch.

Below are the rejects which I saw and below that is my attempt to
resolve it all.  Dan, please go through this with a toothcomb.  I've
just done an mmotm release with all this in it so please do whatever's
needed to verify that it's all working correctly.

--- kernel/memremap.c~mm-devm_memremap_pages-enable-sub-section-remap
+++ kernel/memremap.c
@@ -58,7 +58,7 @@ static unsigned long pfn_first(struct de
 	struct vmem_altmap *altmap = &pgmap->altmap;
 	unsigned long pfn;
 
-	pfn = res->start >> PAGE_SHIFT;
+	pfn = PHYS_PFN(res->start);
 	if (pgmap->altmap_valid)
 		pfn += vmem_altmap_offset(altmap);
 	return pfn;
@@ -95,25 +94,21 @@ static void devm_memremap_pages_release(
 	pgmap->cleanup(pgmap->ref);
 
 	/* pages are dead and unused, undo the arch mapping */
-	align_start = res->start & ~(PA_SECTION_SIZE - 1);
-	align_size = ALIGN(res->start + resource_size(res), PA_SECTION_SIZE)
-		- align_start;
-
-	nid = page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT));
+	nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start)));
 
 	mem_hotplug_begin();
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		pfn = align_start >> PAGE_SHIFT;
+		pfn = PHYS_PFN(res->start);
 		__remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-				align_size >> PAGE_SHIFT, NULL);
+				PHYS_PFN(resource_size(res)), NULL);
 	} else {
-		arch_remove_memory(nid, align_start, align_size,
+		arch_remove_memory(nid, res->start, resource_size(res),
 				pgmap->altmap_valid ? &pgmap->altmap : NULL);
-		kasan_remove_zero_shadow(__va(align_start), align_size);
+		kasan_remove_zero_shadow(__va(res->start), resource_size(res));
 	}
 	mem_hotplug_done();
 
-	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
+	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 	pgmap_array_delete(res);
 	dev_WARN_ONCE(dev, pgmap->altmap.alloc,
 		      "%s: failed to free all reserved pages\n", __func__);
@@ -140,16 +135,13 @@ static void devm_memremap_pages_release(
  */
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
-	resource_size_t align_start, align_size, align_end;
-	struct vmem_altmap *altmap = pgmap->altmap_valid ?
-			&pgmap->altmap : NULL;
 	struct resource *res = &pgmap->res;
 	struct dev_pagemap *conflict_pgmap;
 	struct mhp_restrictions restrictions = {
 		/*
 		 * We do not want any optional features only our own memmap
 		*/
-		.altmap = altmap,
+		.altmap = pgmap->altmap_valid ? &pgmap->altmap : NULL,
 	};
 	pgprot_t pgprot = PAGE_KERNEL;
 	int error, nid, is_ram;
@@ -159,12 +151,7 @@ void *devm_memremap_pages(struct device
 		return ERR_PTR(-EINVAL);
 	}
 
-	align_start = res->start & ~(PA_SECTION_SIZE - 1);
-	align_size = ALIGN(res->start + resource_size(res), PA_SECTION_SIZE)
-		- align_start;
-	align_end = align_start + align_size - 1;
-
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL);
+	conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
 	if (conflict_pgmap) {
 		dev_WARN(dev, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
@@ -220,25 +207,25 @@ void *devm_memremap_pages(struct device
 	 * arch_add_memory().
 	 */
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		error = add_pages(nid, align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, &restrictions);
+		error = add_pages(nid, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), &restrictions);
 	} else {
-		error = kasan_add_zero_shadow(__va(align_start), align_size);
+		error = kasan_add_zero_shadow(__va(res->start), resource_size(res));
 		if (error) {
 			mem_hotplug_done();
 			goto err_kasan;
 		}
 
-		error = arch_add_memory(nid, align_start, align_size,
-					&restrictions);
+		error = arch_add_memory(nid, res->start, resource_size(res),
+				&restrictions);
 	}
 
 	if (!error) {
 		struct zone *zone;
 
 		zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
-		move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, altmap);
+		move_pfn_range_to_zone(zone, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), restrictions.altmap);
 	}
 
 	mem_hotplug_done();

From: Dan Williams <[email-masked]>
Subject: mm/devm_memremap_pages: enable sub-section remap

Teach devm_memremap_pages() about the new sub-section capabilities of
arch_{add,remove}_memory().  Effectively, just replace all usage of
align_start, align_end, and align_size with res->start, res->end, and
resource_size(res).  The existing sanity check will still make sure that
the two separate remap attempts do not collide within a sub-section (2MB
on x86).

Link: http://lkml.kernel.org/r/[email-masked]
Signed-off-by: Dan Williams <[email-masked]>
Tested-by: Aneesh Kumar K.V <[email-masked]>	[ppc64]
Cc: Michal Hocko <[email-masked]>
Cc: Toshi Kani <[email-masked]>
Cc: Jérôme Glisse <[email-masked]>
Cc: Logan Gunthorpe <[email-masked]>
Cc: Oscar Salvador <[email-masked]>
Cc: Pavel Tatashin <[email-masked]>
Cc: David Hildenbrand <[email-masked]>
Cc: Jane Chu <[email-masked]>
Cc: Jeff Moyer <[email-masked]>
Cc: Jonathan Corbet <[email-masked]>
Cc: Mike Rapoport <[email-masked]>
Cc: Vlastimil Babka <[email-masked]>
Cc: Wei Yang <[email-masked]>
Signed-off-by: Andrew Morton <[email-masked]>
---

 kernel/memremap.c |   57 +++++++++++++++++---------------------------
 1 file changed, 23 insertions(+), 34 deletions(-)

--- a/kernel/memremap.c~mm-devm_memremap_pages-enable-sub-section-remap
+++ a/kernel/memremap.c
@@ -54,7 +54,7 @@ static void pgmap_array_delete(struct re
 
 static unsigned long pfn_first(struct dev_pagemap *pgmap)
 {
-	return (pgmap->res.start >> PAGE_SHIFT) +
+	return PHYS_PFN(pgmap->res.start) +
 		vmem_altmap_offset(pgmap_altmap(pgmap));
 }
 
@@ -98,7 +98,6 @@ static void devm_memremap_pages_release(
 	struct dev_pagemap *pgmap = data;
 	struct device *dev = pgmap->dev;
 	struct resource *res = &pgmap->res;
-	resource_size_t align_start, align_size;
 	unsigned long pfn;
 	int nid;
 
@@ -108,25 +107,21 @@ static void devm_memremap_pages_release(
 	dev_pagemap_cleanup(pgmap);
 
 	/* pages are dead and unused, undo the arch mapping */
-	align_start = res->start & ~(SECTION_SIZE - 1);
-	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
-		- align_start;
-
-	nid = page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT));
+	nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start)));
 
 	mem_hotplug_begin();
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		pfn = align_start >> PAGE_SHIFT;
+		pfn = PHYS_PFN(res->start);
 		__remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-				align_size >> PAGE_SHIFT, NULL);
+				 PHYS_PFN(resource_size(res)), NULL);
 	} else {
-		arch_remove_memory(nid, align_start, align_size,
+		arch_remove_memory(nid, res->start, resource_size(res),
 				pgmap_altmap(pgmap));
-		kasan_remove_zero_shadow(__va(align_start), align_size);
+		kasan_remove_zero_shadow(__va(res->start), resource_size(res));
 	}
 	mem_hotplug_done();
 
-	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
+	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
 	pgmap_array_delete(res);
 	dev_WARN_ONCE(dev, pgmap->altmap.alloc,
 		      "%s: failed to free all reserved pages\n", __func__);
@@ -162,13 +157,12 @@ static void dev_pagemap_percpu_release(s
  */
 void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
-	resource_size_t align_start, align_size, align_end;
 	struct resource *res = &pgmap->res;
 	struct dev_pagemap *conflict_pgmap;
 	struct mhp_restrictions restrictions = {
 		/*
 		 * We do not want any optional features only our own memmap
-		*/
+		 */
 		.altmap = pgmap_altmap(pgmap),
 	};
 	pgprot_t pgprot = PAGE_KERNEL;
@@ -225,12 +219,7 @@ void *devm_memremap_pages(struct device
 			return ERR_PTR(error);
 	}
 
-	align_start = res->start & ~(SECTION_SIZE - 1);
-	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
-		- align_start;
-	align_end = align_start + align_size - 1;
-
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL);
+	conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL);
 	if (conflict_pgmap) {
 		dev_WARN(dev, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
@@ -238,7 +227,7 @@ void *devm_memremap_pages(struct device
 		goto err_array;
 	}
 
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL);
+	conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL);
 	if (conflict_pgmap) {
 		dev_WARN(dev, "Conflicting mapping in same section\n");
 		put_dev_pagemap(conflict_pgmap);
@@ -246,7 +235,7 @@ void *devm_memremap_pages(struct device
 		goto err_array;
 	}
 
-	is_ram = region_intersects(align_start, align_size,
+	is_ram = region_intersects(res->start, resource_size(res),
 		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 
 	if (is_ram != REGION_DISJOINT) {
@@ -267,8 +256,8 @@ void *devm_memremap_pages(struct device
 	if (nid < 0)
 		nid = numa_mem_id();
 
-	error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0,
-			align_size);
+	error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(res->start), 0,
+			resource_size(res));
 	if (error)
 		goto err_pfn_remap;
 
@@ -286,16 +275,16 @@ void *devm_memremap_pages(struct device
 	 * arch_add_memory().
 	 */
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		error = add_pages(nid, align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, &restrictions);
+		error = add_pages(nid, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), &restrictions);
 	} else {
-		error = kasan_add_zero_shadow(__va(align_start), align_size);
+		error = kasan_add_zero_shadow(__va(res->start), resource_size(res));
 		if (error) {
 			mem_hotplug_done();
 			goto err_kasan;
 		}
 
-		error = arch_add_memory(nid, align_start, align_size,
+		error = arch_add_memory(nid, res->start, resource_size(res),
 					&restrictions);
 	}
 
@@ -303,8 +292,8 @@ void *devm_memremap_pages(struct device
 		struct zone *zone;
 
 		zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
-		move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, pgmap_altmap(pgmap));
+		move_pfn_range_to_zone(zone, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), restrictions.altmap);
 	}
 
 	mem_hotplug_done();
@@ -316,8 +305,8 @@ void *devm_memremap_pages(struct device
 	 * to allow us to do the work while not holding the hotplug lock.
 	 */
 	memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
-				align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, pgmap);
+				PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), pgmap);
 	percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
 
 	error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
@@ -328,9 +317,9 @@ void *devm_memremap_pages(struct device
 	return __va(res->start);
 
  err_add_memory:
-	kasan_remove_zero_shadow(__va(align_start), align_size);
+	kasan_remove_zero_shadow(__va(res->start), resource_size(res));
  err_kasan:
-	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
+	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
  err_pfn_remap:
 	pgmap_array_delete(res);
  err_array:
_