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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B4E2C98318 for ; Sat, 26 Sep 2026 09:05:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B4C7D6B0088; Sat, 26 Sep 2026 05:05:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AFE7E6B008A; Sat, 26 Sep 2026 05:05:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9ECD16B008C; Sat, 26 Sep 2026 05:05:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 73E7B6B0088 for ; Sat, 26 Sep 2026 05:05:53 -0400 (EDT) Received: from smtpin02.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id D6BE61C3751 for ; Sat, 26 Sep 2026 09:05:52 +0000 (UTC) X-FDA: 85255330944.02.B12D524 Received: from mail-ej2-f41.google.com (mail-ej2-f41.google.com [74.125.228.169]) by imf04.hostedemail.com (Postfix) with ESMTP id 0954F40002 for ; Sat, 26 Sep 2026 09:05:50 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=FxfMuLdu; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of urezki@gmail.com designates 74.125.228.169 as permitted sender) smtp.mailfrom=urezki@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1790413551; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=aeAHyC+9N6Co7JC4GWq1L6y5uc5GROrj5CA6iuWEnjE=; b=AZ9hN2zikDOkPjxPqmQno04t00VMhanaTNWAgBCb33MYPma30Z0a5P/h5ZN5I6co4NyLC9 CYipLXfOj+z/bkRBOrT0Aqd12dXArGP5mJODV9n1LaWAqiw10MaivionS635y6lSVEXFXx CMQBRm8MS1kgoQWqs/tUuSVbc/FrFZw= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=FxfMuLdu; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of urezki@gmail.com designates 74.125.228.169 as permitted sender) smtp.mailfrom=urezki@gmail.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1790413551; b=HGRC9LkbJhyWrPz0eix3GX8kDYk6chF/8w5hmrEv9L+DmzxuJOBHijm1TSp6uzK4YXp/+j jBeL8JwdO72+ctAaNnOkq2T8BCQtRhmGIMhN3YynpU15wj34/hrUN0B+msWfkeQ1aR0UH4 DbigqLy0xN1sWXdmT5+RCv3o/LnvcBQ= Received: by mail-ej2-f41.google.com with SMTP id a640c23a62f3a-c254fa663bfso253906466b.1 for ; Sat, 26 Sep 2026 02:05:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790413549; x=1791018349; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:date:from:from:to:cc:subject :date:message-id:reply-to:content-type; bh=aeAHyC+9N6Co7JC4GWq1L6y5uc5GROrj5CA6iuWEnjE=; b=FxfMuLduWknxEZHPiCgkYnRlVcxDdy3v3UhNzNF2rvkFlkBPama5lEDvliwjbiTl8f IOnEGG4mCo+gDWN7kFSSaAcmcZ0jy6IcAMO7KFgZFZN8lBXeFg90FTV+8/CByPLk4awo TkKZeJidrDfCb5lViJzvvOWXQ5D1Hmvcna+QxkB9OEsiOq756qleX3vGlbzx2fwEyHvD 9mr+ZPXBE85jolye0G7xXiBMJsfBp1jDYFn32eDWH/ha/iud9FAGEfAhO2CkvMwuSNK0 y1slZZepEzw2F5atzPNnHhwmu/d0YqdcKFgT3B92nBIzipRL7m5U4Y3HadXRjgg/suWH /9qw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790413549; x=1791018349; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:date:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=aeAHyC+9N6Co7JC4GWq1L6y5uc5GROrj5CA6iuWEnjE=; b=uAKCMnNfxHon8tcszTHXOx7Hmn3vceRPZ/zx2VK0RL5TkyE0dLmTPZy/yq6wgvRHb3 7k+jzyeNmctIE6TPGCezRK0F2CHEznNvNDYpUYVHVAJBG13IxJ3zCTGXRZ7ox+XOldVP peH4vfqEIfr+MsOOwboXljcF1jw8ZYRpNRSe5NmUegLSnzF/an7e6wiS11ahRUMgyhWC 7YlkselKNSwP17Pv15GuhC5pbkQu/XolxU6rHZZOrkP/m+TppuAaiEj0HmSu1FfP/4aM oKo41Ap+Oh8VVu6qGvdBPnPdYycxh17w347z5/jON/j3Tcv/+KNlQY2r85N2vd67/bVC r99A== X-Forwarded-Encrypted: i=1; AKwUvByPc4+aMvuC43ox69Rq15nmtXSp7c3J2Yoz2dRtPRpHzgzfGULLfJN1jE3CEwhcRCOypOD2F8Wi7Q==@kvack.org X-Gm-Message-State: AFuF++nZdCsZpjaM0n+exVSKRso3+gvexV43QF2qrd7o4QfwA2LbJ2ma tLwUNgqbsstJRvC8R3OUU6KUzM+21RO/vTCp6XaNQBKCwZqmX2PjuyG4 X-Gm-Gg: AYBFou18+CDvJCxcomCNnDlQ1+l2Bb3CePrJgRCyFeiEKstfZcQ4qjygYw/kI1I3Qml QAAxC8cuAabJAAN0MsReo6OQZfaM1Z3v0DTcAXfADwjI+x9UHJB6z0+pufBrsGnhcBQz3k/kv0W w3M4s27kVcWfyJX2MvIQEbVCDP2vbW0N0rg3QitfjGMHp/3YMgIVt8I0ZPdKTfnHV+GZNpNhfBa dNvzB0/QmaMsN/4tLT2rtfJCYATuVonieVSUFoPBx0KqFCMRcry2Zq+Mu1bjXcK1ne7n7xdvDNg cP59s1dNvO7bWrgCjAiuI0n8dg42XuSyv/4JrLDMsnyMdsczS5GBmVT0aWReBeVppdwEqLpU58t gf/yTe0bXnMuhsvzuUaNQ68WjyZeY1yTytkDjnBNcQJ/msEROnNNaq8EEyMHsdyIJfSX9SN1tts XegIUQC5GwKT7kM8jso0sgabB4s20aPwpZs1g= X-Received: by 2002:a17:907:da1:b0:c2d:bc33:7be3 with SMTP id a640c23a62f3a-c2dbc33c16dmr67023066b.47.1790413549220; Sat, 26 Sep 2026 02:05:49 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2ae7357cf3sm224612366b.17.2026.09.26.02.05.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 02:05:48 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Sat, 26 Sep 2026 11:05:45 +0200 To: Andrew Morton Cc: Palla Raghunath , linux-kernel@vger.kernel.org, Shuah Khan , Brigham Campbell , linux-kernel-mentees@lists.linux.dev, syzbot+442828bb356b10813a47@syzkaller.appspotmail.com, Uladzislau Rezki , Baoquan He , linux-mm@kvack.org Subject: Re: [PATCH] mm/vmalloc: do not warn on -ENOMEM from va_clip() in pcpu_get_vm_areas() Message-ID: References: <20260925205450.21262-1-raghunathpalla.0209@gmail.com> <20260925151500.75fcb001ef8cd7f4842e62aa@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925151500.75fcb001ef8cd7f4842e62aa@linux-foundation.org> X-Stat-Signature: goa48ptqrs7ju8gx7qbm1o67q3tbf843 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0954F40002 X-HE-Tag: 1790413550-232392 X-HE-Meta: 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 9rFhpH5E 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 25, 2026 at 03:15:00PM -0700, Andrew Morton wrote: > On Fri, 25 Sep 2026 21:54:49 +0100 Palla Raghunath wrote: > > > When pcpu_get_vm_areas() has to split a free vmap_area in the middle > > (NE_FIT_TYPE), va_clip() needs an extra vmap_area object. It takes the > > per-cpu ne_fit_preload_node if one is there, and otherwise falls back > > to kmem_cache_alloc(GFP_NOWAIT), which may fail and return -ENOMEM. > > pcpu_get_vm_areas() never preloads, and a single call can do more than > > one such split: on a NUMA system it places one area per node group, so > > the first split consumes the preloaded object and the next one depends > > on the GFP_NOWAIT allocation. > > > > That failure is expected and already handled: the recovery path returns > > the areas clipped so far to the free tree, purges lazily freed areas and > > retries. But the error is checked with WARN_ON_ONCE(), so a transient > > allocation failure under memory pressure or fault injection triggers a > > kernel warning, and a panic with panic_on_warn. syzbot hit this on a > > two-node VM while creating a per-cpu BPF array map. > > > > Keep the WARN_ON_ONCE() for errors other than -ENOMEM, which do indicate > > a bug, and take the recovery path either way. This matches what commit > > b9183788a2de ("mm/vmalloc: do not warn on -ENOMEM from va_alloc()") did > > for the other va_clip() caller. > > > > Fixes: 1b23ff80b399 ("mm/vmalloc: invoke classify_va_fit_type() in adjust_va_to_fit_type()") > > Reported-by: syzbot+442828bb356b10813a47@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=442828bb356b10813a47 > > I assume sysbot hit this via fault injection. The report doesn't make this > info easily available. Or maybe it wasn't fault injection. > > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -5107,9 +5107,14 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, > > > > ret = va_clip(&free_vmap_area_root, > > &free_vmap_area_list, va, start, size); > > - if (WARN_ON_ONCE(unlikely(ret))) > > - /* It is a BUG(), but trigger recovery instead. */ > > + if (unlikely(ret)) { > > + /* > > + * -ENOMEM from the GFP_NOWAIT fallback is expected. > > + * Anything else is a BUG(), but trigger recovery instead. > > + */ > > + WARN_ON_ONCE(ret != -ENOMEM); > > Look good. > > The WARN_ON_ONCE() is potentially redundant. We could make va_clip() > remove __GFP_NOWARN from its kmem_cache_alloc() and let the page > allocator do the warn for us. Doesn't matter. > The patch looks good to me also: Reviewed-by: Uladzislau Rezki (Sony) -- Uladzislau Rezki