From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 982A8C4332E for ; Wed, 17 Mar 2021 16:30:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7756664F6C for ; Wed, 17 Mar 2021 16:30:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232577AbhCQQaQ (ORCPT ); Wed, 17 Mar 2021 12:30:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232550AbhCQQ3s (ORCPT ); Wed, 17 Mar 2021 12:29:48 -0400 Received: from mail-io1-xd33.google.com (mail-io1-xd33.google.com [IPv6:2607:f8b0:4864:20::d33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C168C06174A for ; Wed, 17 Mar 2021 09:29:48 -0700 (PDT) Received: by mail-io1-xd33.google.com with SMTP id o11so41683003iob.1 for ; Wed, 17 Mar 2021 09:29:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=kpPDvXNpevj8lhojXAQU6JR+4Ed7UPfrgg63kToNCU4=; b=gkJOrSFWlSBfHRvuR/kZrrzfOVgWfAULd5abmyqDZFyEAtlRS7YHRx532A+3+rSyst //v2OoTBmRMnnV5YC1teiH/2lVeioh51EqYlZWQ08T4qGKdtx5ariGNiqw7bk1x+hTQy CsvOP/d8WPnPeOXHQzZqVP6IQs77rFQEl5exivCcnJPwAaONtIUdGnl3l5bHkIjdamPI luo0gAEGxkwB6oY3epXsJaM3tmydZbTfFKrjEKe6+z6IjK1bf42HHyNaGL50mqmNvF+i lxBiu+bkZvSyaDmEyeI/V+EZBBsYNYWUDL8V81lJtVHSXI04rvRSHWPuxHmVfylVbIPn L2wA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=kpPDvXNpevj8lhojXAQU6JR+4Ed7UPfrgg63kToNCU4=; b=eZvZ00Z3fhfvYNGBtElu/tr1+8VC7fEw3jdyx+Yn9pX2sME22/4Zzdspfl+kz399zu BY82QRZYU3IPEeUPGKC71pDAZ7IT50Oq4EjpsEDg+WOpH7X0AoXojxRi9FDYKoVoOmmw j+XTYVkGmhqOLiQ6/SOazR8XVlGUzRZ5FlaS8gNXIU34KEPPWJfUfAhrfBEQ+UMnk3vp GBPcMwzgpRxGlt6HvOhpPrYaoAbUmUwkdbu9ZOazJYNWm8Hv+YFsLwSDTkcUP2ITphIx wS+l7d7f/+B+9QWHBrxPFfQyjWjBZxEvIA3iUhHz7HcuCZ09cMCzmA19dhecTh+XDhvm YkMw== X-Gm-Message-State: AOAM531OD1zGBh6Lmrbs6+VwVgz7/HPH1DJnR6PfG2N+poM8M9lVJtJa Iyi0il5JjCPI641NjAlOoh1MeRXso/Vsaw== X-Google-Smtp-Source: ABdhPJwkLpeXUdk4UEKaMchVQCqb4alVvAQiXgQR/KWfPLL+/64Z3bVJB9JPjzelJBBKIZM8KEdmtg== X-Received: by 2002:a02:c017:: with SMTP id y23mr3510136jai.3.1615998587624; Wed, 17 Mar 2021 09:29:47 -0700 (PDT) Received: from p1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id h1sm11164271ilo.64.2021.03.17.09.29.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Mar 2021 09:29:47 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: Pavel Begunkov , Jens Axboe Subject: [PATCH 3/9] io_uring: allocate memory for overflowed CQEs Date: Wed, 17 Mar 2021 10:29:37 -0600 Message-Id: <20210317162943.173837-4-axboe@kernel.dk> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210317162943.173837-1-axboe@kernel.dk> References: <20210317162943.173837-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Pavel Begunkov Instead of using a request itself for overflowed CQE stashing, allocate a separate entry. The disadvantage is that the allocation may fail and it will be accounted as lost (see rings->cq_overflow), so we lose reliability in case of memory pressure if the application is driving the CQ ring into overflow. However, it opens a way for for multiple CQEs per an SQE and even generating SQE-less CQEs. Signed-off-by: Pavel Begunkov [axboe: use GFP_ATOMIC | __GFP_ACCOUNT] Signed-off-by: Jens Axboe --- fs/io_uring.c | 99 ++++++++++++++++++++++++--------------------------- 1 file changed, 46 insertions(+), 53 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index dbca1de0be2f..37413a9127b7 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -203,6 +203,11 @@ struct io_mapped_ubuf { struct io_ring_ctx; +struct io_overflow_cqe { + struct io_uring_cqe cqe; + struct list_head list; +}; + struct io_rsrc_put { struct list_head list; union { @@ -1404,41 +1409,33 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx) } /* Returns true if there are no backlogged entries after the flush */ -static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, - struct task_struct *tsk, - struct files_struct *files) +static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force) { struct io_rings *rings = ctx->rings; - struct io_kiocb *req, *tmp; - struct io_uring_cqe *cqe; unsigned long flags; bool all_flushed, posted; - LIST_HEAD(list); if (!force && __io_cqring_events(ctx) == rings->cq_ring_entries) return false; posted = false; spin_lock_irqsave(&ctx->completion_lock, flags); - list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) { - if (!io_match_task(req, tsk, files)) - continue; + while (!list_empty(&ctx->cq_overflow_list)) { + struct io_uring_cqe *cqe = io_get_cqring(ctx); + struct io_overflow_cqe *ocqe; - cqe = io_get_cqring(ctx); if (!cqe && !force) break; - - list_move(&req->compl.list, &list); - if (cqe) { - WRITE_ONCE(cqe->user_data, req->user_data); - WRITE_ONCE(cqe->res, req->result); - WRITE_ONCE(cqe->flags, req->compl.cflags); - } else { - ctx->cached_cq_overflow++; + ocqe = list_first_entry(&ctx->cq_overflow_list, + struct io_overflow_cqe, list); + if (cqe) + memcpy(cqe, &ocqe->cqe, sizeof(*cqe)); + else WRITE_ONCE(ctx->rings->cq_overflow, - ctx->cached_cq_overflow); - } + ++ctx->cached_cq_overflow); posted = true; + list_del(&ocqe->list); + kfree(ocqe); } all_flushed = list_empty(&ctx->cq_overflow_list); @@ -1453,19 +1450,10 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, spin_unlock_irqrestore(&ctx->completion_lock, flags); if (posted) io_cqring_ev_posted(ctx); - - while (!list_empty(&list)) { - req = list_first_entry(&list, struct io_kiocb, compl.list); - list_del(&req->compl.list); - io_put_req(req); - } - return all_flushed; } -static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, - struct task_struct *tsk, - struct files_struct *files) +static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force) { bool ret = true; @@ -1473,7 +1461,7 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force, /* iopoll syncs against uring_lock, not completion_lock */ if (ctx->flags & IORING_SETUP_IOPOLL) mutex_lock(&ctx->uring_lock); - ret = __io_cqring_overflow_flush(ctx, force, tsk, files); + ret = __io_cqring_overflow_flush(ctx, force); if (ctx->flags & IORING_SETUP_IOPOLL) mutex_unlock(&ctx->uring_lock); } @@ -1534,27 +1522,33 @@ static void __io_cqring_fill_event(struct io_kiocb *req, long res, WRITE_ONCE(cqe->user_data, req->user_data); WRITE_ONCE(cqe->res, res); WRITE_ONCE(cqe->flags, cflags); - } else if (ctx->cq_overflow_flushed || - atomic_read(&req->task->io_uring->in_idle)) { - /* - * If we're in ring overflow flush mode, or in task cancel mode, - * then we cannot store the request for later flushing, we need - * to drop it on the floor. - */ - ctx->cached_cq_overflow++; - WRITE_ONCE(ctx->rings->cq_overflow, ctx->cached_cq_overflow); - } else { + return; + } + if (!ctx->cq_overflow_flushed && + !atomic_read(&req->task->io_uring->in_idle)) { + struct io_overflow_cqe *ocqe; + + ocqe = kmalloc(sizeof(*ocqe), GFP_ATOMIC | __GFP_ACCOUNT); + if (!ocqe) + goto overflow; if (list_empty(&ctx->cq_overflow_list)) { set_bit(0, &ctx->sq_check_overflow); set_bit(0, &ctx->cq_check_overflow); ctx->rings->sq_flags |= IORING_SQ_CQ_OVERFLOW; } - io_clean_op(req); - req->result = res; - req->compl.cflags = cflags; - req_ref_get(req); - list_add_tail(&req->compl.list, &ctx->cq_overflow_list); + ocqe->cqe.user_data = req->user_data; + ocqe->cqe.res = res; + ocqe->cqe.flags = cflags; + list_add_tail(&ocqe->list, &ctx->cq_overflow_list); + return; } +overflow: + /* + * If we're in ring overflow flush mode, or in task cancel mode, + * or cannot allocate an overflow entry, then we need to drop it + * on the floor. + */ + WRITE_ONCE(ctx->rings->cq_overflow, ++ctx->cached_cq_overflow); } static void io_cqring_fill_event(struct io_kiocb *req, long res) @@ -2421,7 +2415,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min) * already triggered a CQE (eg in error). */ if (test_bit(0, &ctx->cq_check_overflow)) - __io_cqring_overflow_flush(ctx, false, NULL, NULL); + __io_cqring_overflow_flush(ctx, false); if (io_cqring_events(ctx)) break; @@ -6608,7 +6602,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) /* if we have a backlog and couldn't flush it all, return BUSY */ if (test_bit(0, &ctx->sq_check_overflow)) { - if (!__io_cqring_overflow_flush(ctx, false, NULL, NULL)) + if (!__io_cqring_overflow_flush(ctx, false)) return -EBUSY; } @@ -6901,7 +6895,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, int ret; do { - io_cqring_overflow_flush(ctx, false, NULL, NULL); + io_cqring_overflow_flush(ctx, false); if (io_cqring_events(ctx) >= min_events) return 0; if (!io_run_task_work()) @@ -6933,7 +6927,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, trace_io_uring_cqring_wait(ctx, min_events); do { /* if we can't even flush overflow, don't wait for more */ - if (!io_cqring_overflow_flush(ctx, false, NULL, NULL)) { + if (!io_cqring_overflow_flush(ctx, false)) { ret = -EBUSY; break; } @@ -8596,7 +8590,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) /* if force is set, the ring is going away. always drop after that */ ctx->cq_overflow_flushed = 1; if (ctx->rings) - __io_cqring_overflow_flush(ctx, true, NULL, NULL); + __io_cqring_overflow_flush(ctx, true); xa_for_each(&ctx->personalities, index, creds) io_unregister_personality(ctx, index); mutex_unlock(&ctx->uring_lock); @@ -8754,7 +8748,6 @@ static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx, ret |= io_kill_timeouts(ctx, task, files); ret |= io_run_task_work(); ret |= io_run_ctx_fallback(ctx); - io_cqring_overflow_flush(ctx, true, task, files); if (!ret) break; cond_resched(); @@ -9166,7 +9159,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, */ ret = 0; if (ctx->flags & IORING_SETUP_SQPOLL) { - io_cqring_overflow_flush(ctx, false, NULL, NULL); + io_cqring_overflow_flush(ctx, false); ret = -EOWNERDEAD; if (unlikely(ctx->sq_data->thread == NULL)) { -- 2.31.0