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b=PLS4hCbRspOTf3kxCl5oZZ61sXb0Z3sOjK4oQzOBTNxJmyUvD3LTxjueGtaPbuOnD w6QA3iIrDJXL/dcU2iMc/jTcmFtSMjnhGc0X9pOJJYPC+UYXjjGseYbasBM/PRO7yu cn6FC9+3rvOTZBAyNZGJgtyLzqrB6zqL2Htg3uTM= Date: Tue, 31 Mar 2026 17:49:26 -0700 From: Andrew Morton To: Sergey Senozhatsky Cc: Minchan Kim , Brian Geffon , linux-block@vger.kernel.org, linux-mm@kvack.org, Qu Wenruo , Avinesh Kumar , Christoph Hellwig Subject: Re: [PATCH v3] zram: do not forget to endio for partial discard requests Message-Id: <20260331174926.58ef8dc4d40ac12f8ce3905d@linux-foundation.org> In-Reply-To: <20260331074255.777019-1-senozhatsky@chromium.org> References: <20260331074255.777019-1-senozhatsky@chromium.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1AB0F40003 X-Stat-Signature: x4z9pkq7s5hdg1d7eobqfwismk7pnqyq X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1775004567-267535 X-HE-Meta: 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 nPCfNr+n trw+oCv/BZ7QdJCtPbxwhoyBeko3C0kQj9J87a8x5MwOql3nN5UMzUSqTLrwoxiKC371Ghc36/souamfK3vAtvgyB7WtjeUVNGLrGqMVHDM6mQ1das2PtDmZLsj/NDOWBCzaNmoe98cCUNRs7mKJ9k1cZlRcYQOV8IegLDfErEjRp5RrKIfJn3msTtTRBfTMgFfiNAhGUG9dunoepXyYI19QXu7m/Nl4/2gxNdtsYqCd1eC9dj/pS6na9g4PC6ErL6GbGru/AfydCznTEGfSqxpAjZO/A4E5Oqswb4HiBHD9Nye0PeE0krkvA6p8zAJ0hFvaefpuNu1McO7ELzD+kFl8IR8LMkN27Dfu0Fgn/JqM5Yr+iFE2qAdIMFiWomtuma0PYKe3xQAWG1wvd4O1gLp1fWlIpvr7cXqfMGRsq83blw8XoYLovDbdN8w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 31 Mar 2026 16:42:44 +0900 Sergey Senozhatsky wrote: > As reported by Qu Wenruo, the following > > getconf PAGESIZE > 65536 > blkdiscard -p 4k /dev/zram0 > > takes literally forever to complete. I'm wondering how you measured this interval ;) > zram doesn't support > partial discards and just returns immediately w/o doing any > discard work in such cases. The problem is that we forget > to endio on our way out, so blkdiscard sleeps forever in > submit_bio_wait(). Fix this by jumping to end_bio label, > which does bio_endio(). > > Fixes: 0120dd6e4e202 ("zram: make zram_bio_discard more self-contained") > Signed-off-by: Sergey Senozhatsky > Reported-by: Qu Wenruo > Closes: https://lore.kernel.org/linux-block/92361cd3-fb8b-482e-bc89-15ff1acb9a59@suse.com > Test-by: Qu Wenruo > Cc: Avinesh Kumar > Cc: Christoph Hellwig Thanks. I made several changes to the changelog from the earlier discussion (Anivesh Reported-by:/Closes:) and added a cc:stable. 0120dd6e4e202 was a few years ago so no need to rush this into mainline - target this to the upcoming merge window. From: Sergey Senozhatsky Subject: zram: do not forget to endio for partial discard requests Date: Tue, 31 Mar 2026 16:42:44 +0900 As reported by Qu Wenruo and Avinesh Kumar, the following getconf PAGESIZE 65536 blkdiscard -p 4k /dev/zram0 takes literally forever to complete. zram doesn't support partial discards and just returns immediately w/o doing any discard work in such cases. The problem is that we forget to endio on our way out, so blkdiscard sleeps forever in submit_bio_wait(). Fix this by jumping to end_bio label, which does bio_endio(). Link: https://lkml.kernel.org/r/20260331074255.777019-1-senozhatsky@chromium.org Fixes: 0120dd6e4e202 ("zram: make zram_bio_discard more self-contained") Signed-off-by: Sergey Senozhatsky Reported-by: Qu Wenruo Closes: https://lore.kernel.org/linux-block/92361cd3-fb8b-482e-bc89-15ff1acb9a59@suse.com Tested-by: Qu Wenruo Reported-by: Avinesh Kumar Closes: https://bugzilla.suse.com/show_bug.cgi?id=1256530 Reviewed-by: Christoph Hellwig Cc: Brian Geffon Cc: Jens Axboe Cc: Minchan Kim Signed-off-by: Andrew Morton --- drivers/block/zram/zram_drv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/block/zram/zram_drv.c~zram-do-not-forget-to-endio-for-partial-discard-requests +++ a/drivers/block/zram/zram_drv.c @@ -2678,7 +2678,7 @@ static void zram_bio_discard(struct zram */ if (offset) { if (n <= (PAGE_SIZE - offset)) - return; + goto end_bio; n -= (PAGE_SIZE - offset); index++; @@ -2693,6 +2693,7 @@ static void zram_bio_discard(struct zram n -= PAGE_SIZE; } +end_bio: bio_endio(bio); } _