+ mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch added to -mm tree

+ mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/cma: provide option to opt out from exposing pages on activation failure
has been added to the -mm tree.  Its filename is
     mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch

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------------------------------------------------------
From: Hari Bathini <hbathini@linux.ibm.com>
Subject: mm/cma: provide option to opt out from exposing pages on activation failure

Patch series "powerpc/fadump: handle CMA activation failure appropriately", v3.

Commit 072355c1cf2d ("mm/cma: expose all pages to the buddy if activation
of an area fails") started exposing all pages to buddy allocator on CMA
activation failure.  But there can be CMA users that want to handle the
reserved memory differently on CMA allocation failure.  Provide an option
to opt out from exposing pages to buddy for such cases.

Link: https://lkml.kernel.org/r/20220117075246.36072-1-hbathini@linux.ibm.com
Link: https://lkml.kernel.org/r/20220117075246.36072-2-hbathini@linux.ibm.com
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/cma.h |    2 ++
 mm/cma.c            |   11 +++++++++--
 mm/cma.h            |    1 +
 3 files changed, 12 insertions(+), 2 deletions(-)

--- a/include/linux/cma.h~mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure
+++ a/include/linux/cma.h
@@ -50,4 +50,6 @@ extern bool cma_pages_valid(struct cma *
 extern bool cma_release(struct cma *cma, const struct page *pages, unsigned long count);
 
 extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data);
+
+extern void cma_reserve_pages_on_error(struct cma *cma);
 #endif
--- a/mm/cma.c~mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure
+++ a/mm/cma.c
@@ -131,8 +131,10 @@ not_in_zone:
 	bitmap_free(cma->bitmap);
 out_error:
 	/* Expose all pages to the buddy, they are useless for CMA. */
-	for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
-		free_reserved_page(pfn_to_page(pfn));
+	if (!cma->reserve_pages_on_error) {
+		for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
+			free_reserved_page(pfn_to_page(pfn));
+	}
 	totalcma_pages -= cma->count;
 	cma->count = 0;
 	pr_err("CMA area %s could not be activated\n", cma->name);
@@ -150,6 +152,11 @@ static int __init cma_init_reserved_area
 }
 core_initcall(cma_init_reserved_areas);
 
+void __init cma_reserve_pages_on_error(struct cma *cma)
+{
+	cma->reserve_pages_on_error = true;
+}
+
 /**
  * cma_init_reserved_mem() - create custom contiguous area from reserved memory
  * @base: Base address of the reserved area
--- a/mm/cma.h~mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure
+++ a/mm/cma.h
@@ -30,6 +30,7 @@ struct cma {
 	/* kobject requires dynamic object */
 	struct cma_kobject *cma_kobj;
 #endif
+	bool reserve_pages_on_error;
 };
 
 extern struct cma cma_areas[MAX_CMA_AREAS];
_

Patches currently in -mm which might be from hbathini@linux.ibm.com are

mm-cma-provide-option-to-opt-out-from-exposing-pages-on-activation-failure.patch
powerpc-fadump-opt-out-from-freeing-pages-on-cma-activation-failure.patch