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Wed, 18 Mar 2026 06:07:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C03FC19421; Wed, 18 Mar 2026 06:07:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773814048; bh=yP5/iQJCNcG6ji06jAFAHa49tFVPh+/YzwK+WAC0kSg=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=F6McLun887k2J+kOsvXUUIrKgJoD8v5E54/s0h88YkYuINDVE8c69qjlQSSU5/RAP EscQ5NHtlGYk/FbRpzQbd2Mm0axcS4UbL7UkSVz+jNx1NKgfQ7rqNw7MxLi78yyvbk +/MDRTIrYpD98qMOfAey/DrTKXD7bRjXzy25rMMTQgjGQXToKKq5TU7BMG7/EYPQZv zE5geOvs/oKeaE4pDkFbww7yhfXv9YyVVBcyJYoYOPQxy7AxuTj1e6FCOhAzlIrgmV O458+M89lEesi+ixpOUngaCcc929xGNctXmQd8aO3jOeZWeHl8GIl5mvL8WXLthGSK X2YZnrfMja2Pw== Message-ID: <4acad3d6-ce48-4191-970a-95bcbe8edb01@kernel.org> Date: Wed, 18 Mar 2026 14:07:21 +0800 X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, jianxin.pan@amlogic.com, tuan.zhang@amlogic.com Subject: Re: [PATCH v2] erofs: add GFP_NOIO in the bio completion if needed To: jiucheng.xu@amlogic.com, Gao Xiang , Yue Hu , Jeffle Xu , Sandeep Dhavale , Hongbo Li , Chunhai Guo References: <20260311-origin-dev-v2-1-0657cff690eb@amlogic.com> Content-Language: en-US From: Chao Yu In-Reply-To: <20260311-origin-dev-v2-1-0657cff690eb@amlogic.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2026/3/11 17:11, Jiucheng Xu via B4 Relay wrote: > 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 Reviewed-by: Chao Yu Thanks,