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charset=us-ascii Content-Disposition: inline In-Reply-To: <63477d22-26ef-dd08-a3b0-93931b7d1d16@intel.com> X-Rspamd-Queue-Id: 9BAE51A0006 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: b4hcuahi7q83saxnb6onpmfuz53jmt1e X-HE-Tag: 1687247292-5759 X-HE-Meta: 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 oucOLg1E ZYH8fJ6u4GbMp08AoKEo99mojV15uwAOeMDivdE9wg/1JWHdoLrDY7Zcmopy1mt1o+khTrsEIybCjAA18h4x1CFv1MCiVubSpuWTz2lWEfSO+xrsnNfDMMrQQB3SEPatpwqZgCpCZ3D0gy3KGMxMk2rBruQnV4B7aQZXTzj/0rE/+LGIEGEOOr1PvfOd1lhbnl0TheoPJJO3J6Yk= 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 Mon, Jun 19, 2023 at 04:41:13PM -0700, Dave Hansen wrote: > On 6/19/23 07:46, kirill.shutemov@linux.intel.com wrote: > >>> > >>> Using atomic_set() requires changing tdmr->pamt_4k_base to atomic_t, which is a > >>> little bit silly or overkill IMHO. Looking at the code, it seems > >>> arch_atomic_set() simply uses __WRITE_ONCE(): > >> How about _adding_ a variable that protects tdmr->pamt_4k_base? > >> Wouldn't that be more straightforward than mucking around with existing > >> types? > > What's wrong with simple global spinlock that protects all tdmr->pamt_*? > > It is much easier to follow than a custom serialization scheme. > > Quick, what prevents a: > > spin_lock() => #MC => spin_lock() > > deadlock? > > Plain old test/sets don't deadlock ever. Depends on what you mean; anything that spin-waits will deadlock, doesn't matter if its a test-and-set or not. The thing with these non-maskable exceptions/interrupts is that they must be wait-free. If serialization is required it needs to be try based and accept failure without waiting.