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From:   Kairui Song <ryncsn@gmail.com>
To:     linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        "Huang, Ying" <ying.huang@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Hugh Dickins <hughd@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>, linux-kernel@vger.kernel.org,
        Kairui Song <kasong@tencent.com>
Subject: [PATCH 19/24] shmem, swap: refactor error check on OOM or race
Date:   Mon, 20 Nov 2023 03:47:35 +0800
Message-ID: <20231119194740.94101-20-ryncsn@gmail.com>
In-Reply-To: <20231119194740.94101-1-ryncsn@gmail.com>
References: <20231119194740.94101-1-ryncsn@gmail.com>
Reply-To: Kairui Song <kasong@tencent.com>
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From: Kairui Song <kasong@tencent.com>

It should always check if a swap entry is already swaped in on error,
fix potential false error issue.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/shmem.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 81d129aa66d1..6154b5b68b8f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1857,13 +1857,11 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	page = swapin_page_non_fault(swap, gfp, mpol, ilx, fault_mm, &result);
 	mpol_cond_put(mpol);
 
-	if (PTR_ERR(page) == -EBUSY) {
-		if (!shmem_confirm_swap(mapping, index, swap))
-			return -EEXIST;
+	if (IS_ERR_OR_NULL(page)) {
+		if (!page)
+			error = -ENOMEM;
 		else
-			return -EINVAL;
-	} else if (!page) {
-		error = -ENOMEM;
+			error = -EINVAL;
 		goto failed;
 	} else {
 		folio = page_folio(page);
-- 
2.42.0