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b=igsA26OlqXIJtFbDF1V+Mw9YgpqvdjXpsDYNrJ/enXnrFOBu95AFDgRv5gv3f8LQlMhLRq JiwRBOW7hm7Y8pw7IZQcmwzRVwyE12H7nAyb+KD8bZJYRqRgnc4zdai3N3QtILzFOVVcve UKV1vGYGX6jzgSeLdv4XS12mingZiMw= X-Stat-Signature: dduh1skzbuyb4ms68xmgu7mwj1i9xwxf X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 3F7F4160031 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=Nvidia.com header.s=selector2 header.b=DQCZGEu5; arc=pass ("microsoft.com:s=arcselector9901:i=1"); dmarc=pass (policy=reject) header.from=nvidia.com; spf=none (imf08.hostedemail.com: domain of jhubbard@nvidia.com has no SPF policy when checking 40.107.95.64) smtp.mailfrom=jhubbard@nvidia.com X-HE-Tag: 1656462709-950027 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: On 6/28/22 15:33, Peter Xu wrote: >> The key point is the connection between "locked" and killable. If the comment >> explained why "locked" means "killable", that would help clear this up. The >> NOWAIT sentence is also confusing to me, and adding "mostly NOWAIT" does not >> clear it up either... :) > > Sorry to have a comment that makes it feels confusing. I tried to > explicitly put the comment to be after setting FAULT_FLAG_KILLABLE but > obviously I didn't do my job well.. > > Maybe that NOWAIT thing adds more complexity but not even necessary. > > Would below one more acceptable? > > /* > * We'll only be able to respond to signals when "locked != > * NULL". When with it, we'll always respond to SIGKILL > * (as implied by FAULT_FLAG_KILLABLE above), and we'll > * respond to non-fatal signals only if the GUP user has > * specified FOLL_INTERRUPTIBLE. > */ It looks like part of this comment is trying to document a pre-existing concept, which is that faultin_page() only ever sets FAULT_FLAG_KILLABLE if locked != NULL. The problem I am (personally) having is that I don't yet understand why or how those are connected: what is it about having locked non-NULL that means the process is killable? (Can you explain why that is?) If that were clear, I think I could suggest a good comment wording. thanks, -- John Hubbard NVIDIA