[PATCH] erofs: fix memory leak of LZMA global compressed deduplication

[Gao Xiang]

When stressing microLZMA EROFS images with the new global compressed
deduplication feature enabled (`-Ededupe`), I found some short-lived
temporary pages weren't properly released, which could slowly cause
unexpected OOMs hours later.

Let's fix it now (LZ4 and DEFLATE don't have this issue.)

Fixes: 5c2a64252c5d ("erofs: introduce partial-referenced pclusters")
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
---
 fs/erofs/decompressor_lzma.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
index 73091fbe3ea4..dee10d22ada9 100644
--- a/fs/erofs/decompressor_lzma.c
+++ b/fs/erofs/decompressor_lzma.c
@@ -217,9 +217,12 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 			strm->buf.out_size = min_t(u32, outlen,
 						   PAGE_SIZE - pageofs);
 			outlen -= strm->buf.out_size;
-			if (!rq->out[no] && rq->fillgaps)	/* deduped */
+			if (!rq->out[no] && rq->fillgaps) {	/* deduped */
 				rq->out[no] = erofs_allocpage(pagepool,
 						GFP_KERNEL | __GFP_NOFAIL);
+				set_page_private(rq->out[no],
+						 Z_EROFS_SHORTLIVED_PAGE);
+			}
 			if (rq->out[no])
 				strm->buf.out = kmap(rq->out[no]) + pageofs;
 			pageofs = 0;
-- 
2.24.4