From: Borislav Petkov <bp@alien8.de>
To: Tony Luck <tony.luck@intel.com>
Cc: Jue Wang <juew@google.com>, Ding Hui <dinghui@sangfor.com.cn>,
naoya.horiguchi@nec.com, osalvador@suse.de,
Youquan Song <youquan.song@intel.com>,
huangcun@sangfor.com.cn, x86@kernel.org,
linux-edac@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery
Date: Fri, 20 Aug 2021 19:31:43 +0200 [thread overview]
Message-ID: <YR/m/8PCmCTbogey@zn.tnic> (raw)
In-Reply-To: <20210818002942.1607544-2-tony.luck@intel.com>
On Tue, Aug 17, 2021 at 05:29:40PM -0700, Tony Luck wrote:
> @@ -1287,17 +1291,34 @@ static void kill_me_maybe(struct callback_head *cb)
> }
> }
>
> -static void queue_task_work(struct mce *m, int kill_current_task)
> +static void queue_task_work(struct mce *m, char *msg, int kill_current_task)
> {
> - current->mce_addr = m->addr;
> - current->mce_kflags = m->kflags;
> - current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV);
> - current->mce_whole_page = whole_page(m);
> + int count = ++current->mce_count;
>
> - if (kill_current_task)
> - current->mce_kill_me.func = kill_me_now;
> - else
> - current->mce_kill_me.func = kill_me_maybe;
> + /* First call, save all the details */
> + if (count == 1) {
> + current->mce_addr = m->addr;
> + current->mce_kflags = m->kflags;
> + current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV);
> + current->mce_whole_page = whole_page(m);
> +
> + if (kill_current_task)
> + current->mce_kill_me.func = kill_me_now;
> + else
> + current->mce_kill_me.func = kill_me_maybe;
> + }
> +
> + /* Ten is likley overkill. Don't expect more than two faults before task_work() */
"likely"
> + if (count > 10)
> + mce_panic("Too many machine checks while accessing user data", m, msg);
Ok, aren't we too nasty here? Why should we panic the whole box even
with 10 MCEs? It is still user memory...
IOW, why not:
if (count > 10)
current->mce_kill_me.func = kill_me_now;
and when we return, that user process dies immediately.
> + /* Second or later call, make sure page address matches the one from first call */
> + if (count > 1 && (current->mce_addr >> PAGE_SHIFT) != (m->addr >> PAGE_SHIFT))
> + mce_panic("Machine checks to different user pages", m, msg);
Same question here.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-08-20 17:31 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-06 19:06 [PATCH 0/3] More machine check recovery fixes Tony Luck
2021-07-06 19:06 ` [PATCH 1/3] x86/mce: Change to not send SIGBUS error during copy from user Tony Luck
2021-07-06 19:06 ` [PATCH 2/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-07-06 19:06 ` [PATCH 3/3] x86/mce: Drop copyin special case for #MC Tony Luck
2021-08-18 0:29 ` [PATCH v2 0/3] More machine check recovery fixes Tony Luck
2021-08-18 0:29 ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-08-20 17:31 ` Borislav Petkov [this message]
2021-08-20 18:59 ` Luck, Tony
2021-08-20 19:27 ` Borislav Petkov
2021-08-20 20:23 ` Luck, Tony
2021-08-21 4:51 ` Tony Luck
2021-08-21 21:51 ` Al Viro
2021-08-22 14:36 ` Borislav Petkov
2021-08-20 20:33 ` Luck, Tony
2021-08-22 14:46 ` Borislav Petkov
2021-08-23 15:24 ` Luck, Tony
2021-09-13 9:24 ` Borislav Petkov
2021-09-13 21:52 ` [PATCH v3] " Luck, Tony
2021-09-14 8:28 ` Borislav Petkov
2021-08-18 0:29 ` [PATCH v2 2/3] x86/mce: Change to not send SIGBUS error during copy from user Tony Luck
2021-09-21 7:52 ` [tip: ras/core] " tip-bot2 for Tony Luck
2021-08-18 0:29 ` [PATCH v2 3/3] x86/mce: Drop copyin special case for #MC Tony Luck
2021-09-20 9:13 ` Borislav Petkov
2021-09-20 16:18 ` Luck, Tony
2021-09-20 16:37 ` Borislav Petkov
2021-09-20 16:43 ` Luck, Tony
2021-09-21 7:52 ` [tip: ras/core] " tip-bot2 for Tony Luck
2021-08-18 16:14 ` [PATCH v2 0/3] More machine check recovery fixes Luck, Tony
-- strict thread matches above, loose matches on Subject: below --
2021-01-08 22:22 [PATCH 0/2] Fix infinite machine check loop in futex_wait_setup() Tony Luck
2021-01-11 21:44 ` [PATCH v2 0/3] " Tony Luck
2021-01-11 21:44 ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-11 22:11 ` Andy Lutomirski
2021-01-11 22:20 ` Luck, Tony
2021-01-12 17:00 ` Andy Lutomirski
2021-01-12 17:16 ` Luck, Tony
2021-01-12 17:21 ` Andy Lutomirski
2021-01-12 18:23 ` Luck, Tony
2021-01-12 18:57 ` Andy Lutomirski
2021-01-12 20:52 ` Luck, Tony
2021-01-12 22:04 ` Andy Lutomirski
2021-01-13 1:50 ` Luck, Tony
2021-01-13 4:15 ` Andy Lutomirski
2021-01-13 10:00 ` Borislav Petkov
2021-01-13 16:06 ` Luck, Tony
2021-01-13 16:19 ` Borislav Petkov
2021-01-13 16:32 ` Luck, Tony
2021-01-13 17:35 ` Borislav Petkov
2021-01-14 20:22 ` Borislav Petkov
2021-01-14 21:05 ` Luck, Tony
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