From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ia0-f181.google.com (mail-ia0-f181.google.com [209.85.210.181]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 88C9021F19F for ; Sun, 13 Jan 2013 20:07:29 -0800 (PST) Received: by mail-ia0-f181.google.com with SMTP id s32so3184954iak.40 for ; Sun, 13 Jan 2013 20:07:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=CNdBXmocO21e1q824ESvDhbqiEat1qPOLnG5H5ZOZfI=; b=FLwd0oBzddlmzQIJqbwP4lCPiInspf99x7JPeUzRmSLMSofXSDMDKeoJXTIcKyEYRJ /CZF6xLDUKvSs4gSGeApBgYzuxPFdXg28MM3F8UExuJE3CId6PjznECoNqksWw+tPAsm lbNhVEvSlX/gcBDVuDwq/dYbNTcO1ZKTCXldO6u1rJ9+xMgZyYQ75DEZ2UmhJvDvfa8E gDN1rdo3zZ3uJ0wca8DP0jD5bGA2mSqUWDbguPqwZleozc8+rex3sHWIyuiaDxTQ2fqc rxPVAsNOqsyQbNmr0lAmb45XMnd7ADBXyqNkLuWqfVTwcklHlou5lgQNe78e/vDQxwGP NFIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:x-gm-message-state; bh=CNdBXmocO21e1q824ESvDhbqiEat1qPOLnG5H5ZOZfI=; b=oMnUKrNNK7f6U97KAYR1xCaOCdi28TYhh4Qcv2D/M6FyJ9RVe6GB8tpwM/aPkwL6Ma OTFxs9m/v8OFMeyG9fCNkaSqfW4TiY/cQH5DRxpwa/R6fLI4HnL9rPIV1ieF/wEhfNbY /otGjPrZh/E2dSkT789bWiZAE7twO9QoeI+hlDeVR94Y+veiLRHWdUO6bckh8feRkq18 fq/PLX0apC8W5ELAyVlWUyLukHp4Tww5YGfkffJgtBt8z0heNJDX7mvZHkeGeaflRbjw AsV8tNVpEP39CdJ1ur7PNkPAc/T+Rvj2U2Xv61dHvYnIXTgpS5pJtOAuY/uFdHixduI8 rTqQ== MIME-Version: 1.0 Received: by 10.50.222.132 with SMTP id qm4mr919588igc.99.1358136448804; Sun, 13 Jan 2013 20:07:28 -0800 (PST) Received: by 10.50.161.227 with HTTP; Sun, 13 Jan 2013 20:07:28 -0800 (PST) In-Reply-To: References: <50F32981.9080404@openwrt.org> Date: Sun, 13 Jan 2013 20:07:28 -0800 Message-ID: From: Eric Dumazet To: Felix Fietkau Content-Type: multipart/alternative; boundary=14dae934093f9668f104d337c877 X-Gm-Message-State: ALoCoQkffBzo72JAm0gC0eC2L+tD34ECcnJUQvmfmCJZjC9RFAUw2npGItG+fVXTmX0DRo3a3tNf8tHk2BYJ+zyAYQBYvmnScZKrgfEAkG1p+cZwpSkhLuDRXCbBU6B8cRl3efIsVKlVJ8QTyBBi6VNWpk6PGtSkVezeM5h2jY9rTM0ADXww1KNEyV9fl+kCeglI24D1JWev1LOOgU8+J5v+apw/qTBIZw== Cc: Jerry Chu , cerowrt-devel , Yuchung Cheng Subject: Re: [Cerowrt-devel] TFO crashes cerowrt 3.7.1-1 X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 14 Jan 2013 04:07:29 -0000 --14dae934093f9668f104d337c877 Content-Type: text/plain; charset=ISO-8859-1 Quite frankly I would just remove the BUG_ON() diff --git a/net/core/request_sock.c b/net/core/request_sock.c index c31d9e8..4425148 100644 --- a/net/core/request_sock.c +++ b/net/core/request_sock.c @@ -186,8 +186,6 @@ void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req, struct fastopen_queue *fastopenq = inet_csk(lsk)->icsk_accept_queue.fastopenq; - BUG_ON(!spin_is_locked(&sk->sk_lock.slock) && !sock_owned_by_user(sk)); - tcp_sk(sk)->fastopen_rsk = NULL; spin_lock_bh(&fastopenq->lock); fastopenq->qlen--; On Sun, Jan 13, 2013 at 7:05 PM, Eric Dumazet wrote: > Oh well yes, this doesnt quite work on !SMP. > > And this kind of bug is frequent.... > > See following example : > > commit b9980cdcf2524c5fe15d8cbae9c97b3ed6385563 > Author: Hugh Dickins > Date: Wed Feb 8 17:13:40 2012 -0800 > > mm: fix UP THP spin_is_locked BUGs > > Fix CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_SMP=n CONFIG_DEBUG_VM=y > CONFIG_DEBUG_SPINLOCK=n kernel: spin_is_locked() is then always false, > and so triggers some BUGs in Transparent HugePage codepaths. > > asm-generic/bug.h mentions this problem, and provides a WARN_ON_SMP(x); > but being too lazy to add VM_BUG_ON_SMP, BUG_ON_SMP, WARN_ON_SMP_ONCE, > VM_WARN_ON_SMP_ONCE, just test NR_CPUS != 1 in the existing VM_BUG_ONs. > > Signed-off-by: Hugh Dickins > Cc: Andrea Arcangeli > Cc: > Signed-off-by: Andrew Morton > Signed-off-by: Linus Torvalds > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index b3ffc21..91d3efb 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2083,7 +2083,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot) > { > struct mm_struct *mm = mm_slot->mm; > > - VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock)); > + VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); > > > > > On Sun, Jan 13, 2013 at 1:39 PM, Felix Fietkau wrote: > >> On 2013-01-13 7:03 PM, Eric Dumazet wrote: >> > I suspect a bug in the spin_is_locked() implementation on your arch, as >> > he socket lock should be held at this point. >> I don't think this is an arch implementation bug, this probably happens >> on all !SMP systems. See this bit from include/linux/spinlock_up.h: >> >> #define arch_spin_is_locked(lock) ((void)(lock), 0) >> >> - Felix >> >> > --14dae934093f9668f104d337c877 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Quite frankly I would j= ust remove the BUG_ON()

<= div class=3D"gmail_default" style>
diff --git a= /net/core/request_sock.c b/net/core/request_sock.c
index c31d9e8..4425148 100644
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ = -186,8 +186,6 @@ void reqsk_fastopen_remove(struct sock *sk, struct request= _sock *req,
=A0 =A0 =A0 =A0 struct fastopen_queue *fastope= nq =3D
=A0 =A0 =A0 =A0 =A0 =A0 inet_csk(l= sk)->icsk_accept_queue.fastopenq;
=A0<= /div>
- =A0 =A0 =A0 BUG_ON(!spin_is_locked(&sk->sk_lock.slock) && = !sock_owned_by_user(sk));
-
=A0 =A0 =A0 =A0 tcp_sk(sk)->fastopen_rsk =3D NULL;<= /div>
=A0 =A0 =A0 =A0 spin_lock_bh(&fastopenq->lock);
=A0 =A0 =A0 =A0 fastopenq->qlen--;



On S= un, Jan 13, 2013 at 7:05 PM, Eric Dumazet <edumazet@google.com> wrote:
Oh well yes, this doesnt quite work on !SMP.

And this kind of bug is frequent....=

See following example :

commit b9980cdcf2524c5fe15d8cbae9c97b3ed6385563
Author: Hugh Dickins <hughd@google.com>
Date: =A0 Wed Feb 8 17:13:40 2012 -0800

=A0 =A0 mm: fix UP THP spin_is_locked BUGs
=A0 =A0=A0
=A0 =A0 Fix CONFIG_TRANSPARENT_HUGEPAGE=3Dy CONFIG_SMP=3Dn CONFIG_DEBUG_VM= =3Dy
=A0 =A0 CONFIG_DEBUG_SPINLOCK=3Dn kernel: spin_is_locked() is then always f= alse,
=A0 =A0 and so triggers some BUGs i= n Transparent HugePage codepaths.
=A0 =A0= =A0
=A0 =A0 asm-generic/bug.h mentions this problem, and provides a WARN_ON_SMP= (x);
=A0 =A0 but being too lazy to add VM= _BUG_ON_SMP, BUG_ON_SMP, WARN_ON_SMP_ONCE,
=A0 =A0 VM_WARN_ON_SMP_ONCE, just test NR_CPUS !=3D 1 in the existing VM_= BUG_ONs.
=A0 =A0=A0
= =A0 =A0 Signed-off-by: Hugh Dickins <hughd@google.com>
=A0 =A0 Cc: Andrea Arcangeli <aarcange@redhat.com>
=A0 =A0 Cc: <stable@vger.kernel.org>
=A0 =A0 Signed-off-by: Andrew Morton <akpm@linux-foundation.org<= /a>>
=A0 =A0 Signed-off-by: Linus Torvalds <torvalds@lin= ux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b3ffc21..91d3efb 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2083,7 +2083,= 7 @@ static void collect_mm_slot(struct mm_slot *mm_slot)
=A0{
=A0 =A0= =A0 =A0 struct mm_struct *mm =3D mm_slot->mm;
=A0
- =A0 =A0 =A0 VM_BUG_ON(!spi= n_is_locked(&khugepaged_mm_lock));
+ =A0 =A0 =A0 VM_BUG_ON(NR_CPUS !=3D 1 &&a= mp; !spin_is_locked(&khugepaged_mm_lock));



<= br>
On Sun, Jan 13, 2013 at 1:39 PM, Felix Fietkau <nbd@openwrt.org> wrote:
On 2013-01-13 7:03 PM, Eric Dumazet wrote:
> I suspect a bug in the spin_is_locked() implementation on your arch, a= s
> he socket lock should be held at this point.
I don't think this is an arch implementation bug, this probably h= appens
on all !SMP systems. See this bit from include/linux/spinlock_up.h:

#define arch_spin_is_locked(lock) =A0 ((void)(lock), 0)

- Felix



--14dae934093f9668f104d337c877--