lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [day] [month] [year] [list]
Date: Thu,  8 Feb 2024 10:37:01 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-mm@...ck.org
Cc: Anshuman Khandual <anshuman.khandual@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	Mike Rapoport <rppt@...nel.org>,
	Mike Kravetz <mike.kravetz@...cle.com>,
	Minchan Kim <minchan@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: [RFC] mm/cma: Move cma_mutex into 'struct cma'

Concurrent cma_alloc() requests might race with each other, inside the same
CMA heap area. These races could not happen between two different CMA areas
as their pfn ranges will be non overlapping. Let's just reduce the scope of
the 'cma_mutex' from being system wide to CMA heap area specific, allowing
concurrent cma_alloc() requests in different CMA heap areas.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Hildenbrand <david@...hat.com>
Cc: Mike Rapoport <rppt@...nel.org>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Minchan Kim <minchan@...nel.org>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
This patch is slightly tested, although wanted to get some initial feedback
on whether the scope of this CMA mutex should be reduced down in principle.

 mm/cma.c | 6 +++---
 mm/cma.h | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 4f95266eba1d..d6a52dec1b19 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -33,7 +33,6 @@
 
 struct cma cma_areas[MAX_CMA_AREAS];
 unsigned cma_area_count;
-static DEFINE_MUTEX(cma_mutex);
 
 phys_addr_t cma_get_base(const struct cma *cma)
 {
@@ -111,6 +110,7 @@ static void __init cma_activate_area(struct cma *cma)
 		init_cma_reserved_pageblock(pfn_to_page(pfn));
 
 	spin_lock_init(&cma->lock);
+	mutex_init(&cma->cma_mutex);
 
 #ifdef CONFIG_CMA_DEBUGFS
 	INIT_HLIST_HEAD(&cma->mem_head);
@@ -460,10 +460,10 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 		spin_unlock_irq(&cma->lock);
 
 		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
-		mutex_lock(&cma_mutex);
+		mutex_lock(&cma->cma_mutex);
 		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
 				     GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0));
-		mutex_unlock(&cma_mutex);
+		mutex_unlock(&cma->cma_mutex);
 		if (ret == 0) {
 			page = pfn_to_page(pfn);
 			break;
diff --git a/mm/cma.h b/mm/cma.h
index ad61cc6dd439..d84183e1caba 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -16,6 +16,7 @@ struct cma {
 	unsigned long   *bitmap;
 	unsigned int order_per_bit; /* Order of pages represented by one bit */
 	spinlock_t	lock;
+	struct mutex	cma_mutex;
 #ifdef CONFIG_CMA_DEBUGFS
 	struct hlist_head mem_head;
 	spinlock_t mem_head_lock;
-- 
2.25.1


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ