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[31.46.245.48]) by smtp.gmail.com with ESMTPSA id rp5-20020a170906d96500b0098e78ff1a87sm17405863ejb.120.2023.10.02.12.06.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 12:06:14 -0700 (PDT) Sender: Ingo Molnar Date: Mon, 2 Oct 2023 21:06:12 +0200 From: Ingo Molnar To: Zhiquan Li Cc: x86@kernel.org, linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, bp@alien8.de, tony.luck@intel.com, naoya.horiguchi@nec.com, Youquan Song Subject: Re: [PATCH RESEND v2] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic Message-ID: References: <20230914030539.1622477-1-zhiquan1.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230914030539.1622477-1-zhiquan1.li@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Zhiquan Li wrote: > Kdump can exclude the HWPosion page to avoid touch the error page > again, the prerequisite is the PG_hwpoison page flag is set. > However, for some MCE fatal error cases, there is no opportunity > to queue a task for calling memory_failure(), as a result, > the capture kernel touches the error page again and panics. > > Add function mce_set_page_hwpoison_now() which marks a page as > HWPoison before kernel panic() for MCE error, so that the dump > program can check and skip the error page and prevent the capture > kernel panic. > > [Tony: Changed TestSetPageHWPoison() to SetPageHWPoison()] > > Co-developed-by: Youquan Song > Signed-off-by: Youquan Song > Signed-off-by: Zhiquan Li > Signed-off-by: Tony Luck > Reviewed-by: Naoya Horiguchi > > --- > V2 RESEND notes: > - No changes on this, just rebasing as v6.6-rc1 is out. > - Added the tag from Naoya. > Link: https://lore.kernel.org/all/20230719211625.298785-1-tony.luck@intel.com/#t > > Changes since V1: > - Revised the commit message as per Naoya's suggestion. > - Replaced "TODO" comment in code with comments based on mailing list > discussion on the lack of value in covering other page types. > Link: https://lore.kernel.org/all/20230127015030.30074-1-tony.luck@intel.com/ > --- > arch/x86/kernel/cpu/mce/core.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 6f35f724cc14..2725698268f3 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -156,6 +156,22 @@ void mce_unregister_decode_chain(struct notifier_block *nb) > } > EXPORT_SYMBOL_GPL(mce_unregister_decode_chain); > > +/* > + * Kdump can exclude the HWPosion page to avoid touch the error page again, > + * the prerequisite is the PG_hwpoison page flag is set. However, for some > + * MCE fatal error cases, there are no opportunity to queue a task > + * for calling memory_failure(), as a result, the capture kernel panics. > + * This function marks the page as HWPoison before kernel panic() for MCE. > + */ The English in this commit is *atrocious*, both in the changelog and in the comments - how on Earth did 'Posion' typo and half a dozen other typos and bad grammar survive ~3 iterations and a Reviewed-by tag?? The version below fixes up the worst, but I suspect that's not the only problem with this patch... Thanks, Ingo ================> From: Zhiquan Li Date: Thu, 14 Sep 2023 11:05:39 +0800 Subject: [PATCH] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic Kdump can exclude the HWPoison page to avoid touching the error page again, the prerequisite is the PG_hwpoison page flag is set. However, for some MCE fatal error cases, there is no opportunity to queue a task for calling memory_failure(), and as a result, the capture kernel touches the error page again and panics. Add the mce_set_page_hwpoison_now() function, which marks a page as HWPoison before kernel panic() for MCE error, so that the dump program can check and skip the error page and prevent the capture kernel panic. [ Tony: Changed TestSetPageHWPoison() to SetPageHWPoison() ] [ mingo: Fixed the comments & changelog ] Co-developed-by: Youquan Song Signed-off-by: Youquan Song Signed-off-by: Zhiquan Li Signed-off-by: Tony Luck Signed-off-by: Ingo Molnar Reviewed-by: Naoya Horiguchi Cc: Borislav Petkov Link: https://lore.kernel.org/all/20230719211625.298785-1-tony.luck@intel.com/#t --- arch/x86/kernel/cpu/mce/core.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 6f35f724cc14..1a14e8233c5a 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -156,6 +156,22 @@ void mce_unregister_decode_chain(struct notifier_block *nb) } EXPORT_SYMBOL_GPL(mce_unregister_decode_chain); +/* + * Kdump can exclude the HWPoison page to avoid touching the error page again, + * the prerequisite is that the PG_hwpoison page flag is set. However, for some + * MCE fatal error cases, there is no opportunity to queue a task + * for calling memory_failure(), and as a result, the capture kernel panics. + * This function marks the page as HWPoison before kernel panic() for MCE. + */ +static void mce_set_page_hwpoison_now(unsigned long pfn) +{ + struct page *p; + + p = pfn_to_online_page(pfn); + if (p) + SetPageHWPoison(p); +} + static void __print_mce(struct mce *m) { pr_emerg(HW_ERR "CPU %d: Machine Check%s: %Lx Bank %d: %016Lx\n", @@ -286,6 +302,8 @@ static noinstr void mce_panic(const char *msg, struct mce *final, char *exp) if (!fake_panic) { if (panic_timeout == 0) panic_timeout = mca_cfg.panic_timeout; + if (final && (final->status & MCI_STATUS_ADDRV)) + mce_set_page_hwpoison_now(final->addr >> PAGE_SHIFT); panic(msg); } else pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg);