From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com,
Ian.Campbell@citrix.com, hpa@zytor.com, x86@kernel.org
Subject: [PATCH] extend_brk and fixes to users of extend_brk (v1).
Date: Tue, 31 Jul 2012 06:42:53 -0400 [thread overview]
Message-ID: <1343731376-20658-1-git-send-email-konrad.wilk@oracle.com> (raw)
In v3.5 I've added some patches that during boot-time and add more
entries to the P2M tree: http://lists.xen.org/archives/html/xen-devel/2012-04/msg01152.html
which worked great on all my machines. But there were some folks
who reported that it caused them at bootup to hit this:
(XEN) domain_crash_sync called from entry.S
(XEN) CPU: 0
(XEN) RIP: e033:[<ffffffff818aad3b>]
(XEN) RFLAGS: 0000000000000206 EM: 1 CONTEXT: pv guest
(XEN) rax: ffffffff81a7c000 rbx: 000000000000003d rcx: 0000000000001000
(XEN) rdx: ffffffff81a7b000 rsi: 0000000000001000 rdi: 0000000000001000
(XEN) rbp: ffffffff81801cd8 rsp: ffffffff81801c98 r8: 0000000000100000
(XEN) r9: ffffffff81a7a000 r10: 0000000000000001 r11: 0000000000000003
(XEN) r12: 0000000000000004 r13: 0000000000000004 r14: 000000000000003d
(XEN) r15: 00000000000001e8 cr0: 000000008005003b cr4: 00000000000006f0
(XEN) cr3: 0000000125803000 cr2: 0000000000000000
(XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: e02b cs: e033
(XEN) Guest stack trace from rsp=ffffffff81801c98:
The failure was that my patches depended on the __brk_base to be large.
On v3.5 due to some other patches (not sure which ones) the space is quite
large (around ~4MB) while in previous kernels its ~344kB. But depending
on the compiler to fix my mistake is not really the best way. So patch:
[PATCH 2/3] xen/p2m: Reserve 4MB of _brk space for P2M leafs when
fixes this, while
[PATCH 1/3] xen/mmu/p2m: Check extend_brk for NULL
gets in line with the DMI code to check extend_brk for NULL, and lastly:
[PATCH 3/3] x86: Let extend_brk return a NULL pointer instead of
makes extend_brk not do BUG_ON and instead just return NULL. This allows
us to handle the bootup issues more gracefully.
Note, I've also posted another variant of this:
http://lists.xen.org/archives/html/xen-devel/2012-07/msg01401.html
which Ian pointed out is a bit fragile.
Looking forward to your comments.
next reply other threads:[~2012-07-31 10:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-31 10:42 Konrad Rzeszutek Wilk [this message]
2012-07-31 10:42 ` [PATCH 1/3] xen/mmu/p2m: Check extend_brk for NULL Konrad Rzeszutek Wilk
2012-07-31 13:48 ` Konrad Rzeszutek Wilk
2012-07-31 10:42 ` [PATCH 2/3] xen/p2m: Reserve 4MB of _brk space for P2M leafs when populating back Konrad Rzeszutek Wilk
2012-07-31 10:42 ` [PATCH 3/3] x86: Let extend_brk return a NULL pointer instead of just BUG_ON Konrad Rzeszutek Wilk
2012-07-31 15:49 ` [PATCH] extend_brk and fixes to users of extend_brk (v1) H. Peter Anvin
2012-07-31 16:15 ` Konrad Rzeszutek Wilk
2012-07-31 16:41 ` [Xen-devel] " Jan Beulich
2012-07-31 17:29 ` Konrad Rzeszutek Wilk
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