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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260311-origin-dev-v2-1-0657cff690eb@amlogic.com> X-B4-Tracking: v=1; b=H4sIAMIxsWkC/23MQQ7CIBCF4as0s3YMIKXWlfcwXTR0oJPY0oAhm oa7i127/F/yvh0SRaYEt2aHSJkTh7WGOjVg53H1hDzVBiWUERcpMUT2vOJEGaXtjWm7/qqEhnr YIjl+H9hjqD1zeoX4Oewsf+tfJkuUqEWrNDnROSfu4/IMnu3ZhgWGUsoXgsB0KaYAAAA= X-Change-ID: 20260311-origin-dev-1c9665798204 To: Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Sandeep Dhavale , Hongbo Li , Chunhai Guo Cc: linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, jianxin.pan@amlogic.com, tuan.zhang@amlogic.com, Jiucheng Xu , Gao Xiang X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1773220291; l=2158; i=jiucheng.xu@amlogic.com; s=20250821; h=from:subject:message-id; bh=YPPl1F3AUiL8XQFRy+eFl96JoDCQD8dYm64Zhy8f3cs=; b=E0Upnfawkos/3AiYtmkE1dhVITJ+d/UynPpDQdaMAbmgFjnARJUiz49lEt2IJfK9wcudy6z32 CLHKK3xLA6RBs+TwUnC/p76zC/qg7Zq4nsHsjVz3okyIOqW5cUMQBAJ X-Developer-Key: i=jiucheng.xu@amlogic.com; a=ed25519; pk=Q18IjkdWCCuncSplyu+dYqIrm+n42glvoLFJTQqpb2o= X-Endpoint-Received: by B4 Relay for jiucheng.xu@amlogic.com/20250821 with auth_id=498 X-Original-From: Jiucheng Xu Reply-To: jiucheng.xu@amlogic.com From: Jiucheng Xu The bio completion path in the process context (e.g. dm-verity) will directly call into decompression rather than trigger another workqueue context for minimal scheduling latencies, which can then call vm_map_ram() with GFP_KERNEL. Due to insufficient memory, vm_map_ram() may generate memory swapping I/O, which can cause submit_bio_wait to deadlock in some scenarios. Trimmed down the call stack, as follows: f2fs_submit_read_io submit_bio //bio_list is initialized. mmc_blk_mq_recovery z_erofs_endio vm_map_ram __pte_alloc_kernel __alloc_pages_direct_reclaim shrink_folio_list __swap_writepage submit_bio_wait //bio_list is non-NULL, hang!!! Use memalloc_noio_{save,restore}() to wrap up this path. Reviewed-by: Gao Xiang Signed-off-by: Jiucheng Xu --- Changes in v2: - Reword the commit message. - Link to v1: https://lore.kernel.org/r/20260311-origin-dev-v1-1-40524ef07ff0@amlogic.com --- fs/erofs/zdata.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 3977e42b9516861bf3d59c072b6b8aaa6898dd8a..fe8121df9ef2f2404fc6e3f0fbbd6367f9ec2c67 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1445,6 +1445,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io, int bios) { struct erofs_sb_info *const sbi = EROFS_SB(io->sb); + int gfp_flag; /* wake up the caller thread for sync decompression */ if (io->sync) { @@ -1477,7 +1478,9 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io, sbi->sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON; return; } + gfp_flag = memalloc_noio_save(); z_erofs_decompressqueue_work(&io->u.work); + memalloc_noio_restore(gfp_flag); } static void z_erofs_fill_bio_vec(struct bio_vec *bvec, --- base-commit: 11439c4635edd669ae435eec308f4ab8a0804808 change-id: 20260311-origin-dev-1c9665798204 Best regards, -- Jiucheng Xu