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Thu, 10 Jul 2025 07:35:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 4gZuMU1tb2jzJAAAD6G6ig (envelope-from ); Thu, 10 Jul 2025 07:35:41 +0000 Message-ID: Date: Thu, 10 Jul 2025 09:35:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: implement "memory.oops_if_bad_pte=1" boot option To: Alexey Dobriyan , akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko References: <4e1b7d2d-ed54-4e0a-a0a4-906b14d9cd41@p183> Content-Language: en-US From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <4e1b7d2d-ed54-4e0a-a0a4-906b14d9cd41@p183> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: AC73D1C0009 X-Stat-Signature: sjqaq1amxhc35dnsxqur1t4p5kdy36zi X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1752132943-934912 X-HE-Meta: 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 v+0jnpp1 uN71zHZ62QYoO3CZWgidc0yF/iltvYG/vVIhuc8hJD6WC5+ytt4WNleuGNwaYnq6rFwt24c3mkr9XL3DHL2SZUJQ3OeBt0imrbL5UmfPZDRFhrGa0CJSMkPVg9CfDZLl4s9qv6LKIMM0yIU7bYK6E9lRqvMpXjtOwEACiLN3mq+QB6GNXwYVuDnJmTm8j7qGgXBJBGuZ7Uhdb3aT+ih8oTCdXi60fJnUL/n37SfkzJT7a1kdHywXQmX7XEp8zPLbHqfhoR2AMsfUT+5tcl5dfhIAabj1WeU9VpMJjXBUIw1avf07+h6ZjwHsAe77+9kGH2vzOEB7MvXB9YN/kdXEOMGvSAKD6jiRbIgeDQblW5JQROvLpiZbxAjtAB1m7EI2crMMI54WgZF40UYD/aMJp7nraDC5AiaYAMVtVWSbHih8k7Co= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/9/25 20:10, Alexey Dobriyan wrote: > Implement > > memory.oops_if_bad_pte=1 > > boot option which oopses the machine instead of dreadful > > BUG: Bad page map in process > > message. > > This is intended > for people who want to panic at the slightest provocation and > for people who ruled out hardware problems which in turn means that > delaying vmcore collection is counter-productive. > > Linux doesn't (never?) panicked on PTE corruption and even implemented > ratelimited version of the message meaning it can go for minutes and > even hours without anyone noticing which is exactly the opposite of what > should be done to facilitate debugging. > > Not enabled by default. > > Not advertised. > > Signed-off-by: Alexey Dobriyan Could we just reuse the existing panic_on_oops? Would anyone want to panic in this particular without the others, or vice versa? > --- > > mm/memory.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index b0cda5aab398..90b92b312802 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -42,6 +42,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -480,6 +481,13 @@ static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) > add_mm_counter(mm, i, rss[i]); > } > > +/* > + * Oops instead of printing "Bad page map in process" message and > + * trying to continue. > + */ > +static bool oops_if_bad_pte __ro_after_init = false; > +module_param(oops_if_bad_pte, bool, 0444); > + > /* > * This function is called to print an error when a bad pte > * is found. For example, we might have a PFN-mapped pte in > @@ -490,6 +498,13 @@ static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) > static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, > pte_t pte, struct page *page) > { > + /* > + * This line is a formality to collect vmcore ASAP. Real bug > + * (hardware or software) happened earlier, current registers and > + * backtrace aren't interesting. > + */ > + BUG_ON(oops_if_bad_pte); > + > pgd_t *pgd = pgd_offset(vma->vm_mm, addr); > p4d_t *p4d = p4d_offset(pgd, addr); > pud_t *pud = pud_offset(p4d, addr);