linux-kernel - [PATCH] mm/cma: Don't treat bad input arguments for cma

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Date: Thu,  1 Feb 2024 08:07:14 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-mm@...ck.org
Cc: Anshuman Khandual <anshuman.khandual@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] mm/cma: Don't treat bad input arguments for cma_alloc() as its failure

Invalid cma_alloc() input scenarios - including excess allocation request
should neither be counted as CMA_ALLOC_FAIL nor 'cma->nr_pages_failed' be
updated when applicable with CONFIG_CMA_SYSFS. This also drops 'out' jump
label which has become redundant.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
Also inclined to fold (!count) check into the first one i.e (!cma || ..)
before the pr_debug() output. This applies on v6.8-rc2.

 mm/cma.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 7c09c47e530b..464fb4c8b4f0 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -438,13 +438,13 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	int ret = -ENOMEM;
 
 	if (!cma || !cma->count || !cma->bitmap)
-		goto out;
+		return page;
 
 	pr_debug("%s(cma %p, name: %s, count %lu, align %d)\n", __func__,
 		(void *)cma, cma->name, count, align);
 
 	if (!count)
-		goto out;
+		return page;
 
 	trace_cma_alloc_start(cma->name, count, align);
 
@@ -454,7 +454,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
 
 	if (bitmap_count > bitmap_maxno)
-		goto out;
+		return page;
 
 	for (;;) {
 		spin_lock_irq(&cma->lock);
@@ -515,14 +515,12 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
 	}
 
 	pr_debug("%s(): returned %p\n", __func__, page);
-out:
 	if (page) {
 		count_vm_event(CMA_ALLOC_SUCCESS);
 		cma_sysfs_account_success_pages(cma, count);
 	} else {
 		count_vm_event(CMA_ALLOC_FAIL);
-		if (cma)
-			cma_sysfs_account_fail_pages(cma, count);
+		cma_sysfs_account_fail_pages(cma, count);
 	}
 
 	return page;
-- 
2.25.1