From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
hongfeng <hongfeng@marvell.com>,
david@gibson.dropbear.id.au
Subject: Regression with orderly_poweroff()
Date: Tue, 12 Mar 2013 14:25:12 +1100 [thread overview]
Message-ID: <1363058712.4534.12.camel@pasglop> (raw)
Hi Linus !
A couple of weeks ago, David sent an email that went unanswered about a
regression concerning orderly_poweroff(). I think the original patch
causing it should be reverted, here's the actual email with the
explanation:
<<<
Subject: orderly_poweroff() is no longer safe in atomic context
Commit 6c0c0d4d1080840eabb3d055d2fd81911111c5fd "poweroff: fix bug in
orderly_poweroff()" apparently fixes one bug in orderly_poweroff(),
but introduces another. The comments on orderly_poweroff() claim it
can be called from any context - and indeed we call it from interrupt
context in arch/powerpc/platforms/pseries/ras.c for example. But
since that commit this is no longer safe, since
call_usermodehelper_fns() is not safe in interrupt context without the
UMH_NO_WAIT option.
I'm having trouble understanding the commit message to see what the
original bug being fixed was. Specifically I can't make sense of:
| The bug here is, step 1 is always successful with param
| UMH_NO_WAIT, which obey the design goal of orderly_poweroff.
And without understanding the original bug, I'm not sure what the
correct fix is.
>>>
Cheers,
Ben.
next reply other threads:[~2013-03-12 3:25 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-12 3:25 Benjamin Herrenschmidt [this message]
2013-03-12 14:46 ` Regression with orderly_poweroff() Linus Torvalds
2013-03-12 17:46 ` Oleg Nesterov
2013-03-12 17:54 ` Lucas De Marchi
2013-03-12 18:22 ` Oleg Nesterov
2013-03-12 18:42 ` Linus Torvalds
2013-03-12 19:11 ` Oleg Nesterov
2013-03-12 19:20 ` Linus Torvalds
2013-03-12 20:35 ` Oleg Nesterov
2013-03-13 17:46 ` [PATCH 0/1] poweroff: change orderly_poweroff() to use schedule_work() Oleg Nesterov
2013-03-13 17:47 ` [PATCH 1/1] " Oleg Nesterov
2013-03-14 22:28 ` Andrew Morton
2013-03-15 16:39 ` Oleg Nesterov
2013-03-16 20:23 ` [PATCH 0/2] finx argv_split() vs sysctl race Oleg Nesterov
2013-03-16 20:23 ` [PATCH 1/2] teach argv_split() to handle the mutable strings Oleg Nesterov
2013-03-18 16:03 ` [PATCH v2 " Oleg Nesterov
2013-03-18 21:53 ` [PATCH " Andrew Morton
2013-03-19 19:54 ` [PATCH -mm] argv_split-teach-it-to-handle-mutable-strings-fix-2 Oleg Nesterov
2013-03-16 20:24 ` [PATCH 2/2] set_task_comm: kill the pointless memset() + wmb() Oleg Nesterov
2013-03-16 20:32 ` [PATCH 0/2] finx argv_split() vs sysctl race Andi Kleen
2013-03-16 20:45 ` Oleg Nesterov
2013-03-16 20:56 ` Andi Kleen
2013-03-16 21:23 ` Oleg Nesterov
2013-03-16 21:54 ` Andi Kleen
2013-03-17 14:15 ` Oleg Nesterov
2013-03-18 16:03 ` Oleg Nesterov
2013-03-13 23:35 ` [PATCH 0/1] poweroff: change orderly_poweroff() to use schedule_work() Lucas De Marchi
2013-03-12 20:13 ` Regression with orderly_poweroff() Andi Kleen
2013-03-12 19:28 ` Benjamin Herrenschmidt
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