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[2a03:2880:31ff:b::face:b00c]) by smtp.gmail.com with ESMTPSA id wh11-20020a1709078f8b00b00a26f6b8be1csm47026ejc.75.2024.01.24.08.24.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jan 2024 08:24:22 -0800 (PST) Date: Wed, 24 Jan 2024 08:24:20 -0800 From: Breno Leitao To: Marco Elver Cc: andrey.konovalov@linux.dev, Andrew Morton , Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Oscar Salvador , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: Re: [PATCH v4 12/22] lib/stackdepot: use read/write lock Message-ID: References: <9f81ffcc4bb422ebb6326a65a770bf1918634cbb.1700502145.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: 8mqpuy4y1buunw9g45w9mj49czn5ts7p X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: CF31B80022 X-HE-Tag: 1706113464-811681 X-HE-Meta: U2FsdGVkX1+pXmN5a/r4mLstVBkHbqspbaEQYUHeO6OWukjMs5OR81S8U0ntbAl1njHrnS//fjPBpxiK/1/uc2KvCkeqBssPn06TsBA8ma6fYvm92rsOiZkccd9HovvOD3HnHZ+aG4OPEyWttSkoj60o9fZkEe0kdz82oZh0ID5jXPW2o6I3cqv5lfWPaGkcmxoGZEz4sLgYGOmbQKeT1kNj+WEdrQcIdtDM6Eqd/v7OpBAwuY7TyAmiDgi9J1UK3M+1Qj4vMJPcCDgdrcIORL3FYCvqQYIwXuMn8WH+DAtiYUPt1LZ1MNmkUwzETYIjZnVE03qEWjK44khdqz+nWEJEUG2eLUpTqvG0ybyE+pIiopyDJg6ZhTnnrncEcFkpKBxvCjG96793XA8x5PBJ+Oew0KfalTaR0fmkKl1Df7tgAzpSrHMEfleQwRVm+AKAdgwlh2yanN48FLDae2XTKsXVigZWspRECCKcH1NUvo7kr6nMWDPNGnNr69tI8XVFIQ8YCrJIi+gOUH+L0mGQVQvULBfZs4epnWm/M2UuOhGJBL8bsx2O0PhmOI4oRc8MsJjXTiYkIDbehuBNV8KTqm4zf03AyR878dti5SAQAwentQPMYDX2wievPSGCcfgWW5SQOhN7HVSn7XCUdy2yKj58DVxNHAn7niCsRC48lDXThJp1xzGpxN/LU2YJOsMAvDNxhEK5oUIyyq3YutG1b7KOftiiH3YuccxuAsjqRdxIYbJ8dld9bOfhya45jNt+Mbt3lHw64IFGDFl6MRdXt6AgKqJ2fcAJBIdUwbFaUEfeC4nHvuBrYk4jSfrgLgHCjNkZjmSEkyHO+X4RCbgSjr8e+gQOphSieOtecIC4jj5k3H5tKcLPAkVSFnYuqDuW6U4d+L0R25tdGUW7TmcgjgbPigDDHD0708zlZSt2XjJ3EPrDPpwLkGY8dfY6Mut8rp1j8zWVz6du5zTe/4U HKFXjAyP /BlGfeeANZgpjrTtRJ4tT3sMi09GykgqNT0eUCIB765E0AGEHXekjUPB055kCk7wptPwwmjFhIqmPMZGPgYyVvEGQSDVG9anxWWv6mq7qEc0px+1FnaqmcQPLfLFHqT0tZsNn0viin8dqd8AXD+dgHVCcbfjh01s+/dCLdKsk4SZBGHuQQPk+fn7QoWeUGljPxdYEIxugwWnKue9Jr/6BGVHqmQYjStr0UhtknV1apstZaix23NtIRCccCVgWf8vfHZL5OV7WAzt+72uUuD9eF3DOwyWmQg/g4UQbEYV4xliF7Ew5kf/GasLKmokEYrXY6VCG9i3FVj8wKHs8CPd5gAM7F5fdoiETbo7n1IRDI8hZNl3HVhKWNdOvpCUiJNzPjOEnckrOFbju6S+Z0yIO77SHkjWHgxm6mIWMCsxHFJFEb+YgMOpX9QuZzgf7O6x2cldJ 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 Wed, Jan 24, 2024 at 03:21:26PM +0100, Marco Elver wrote: > On Wed, 24 Jan 2024 at 15:16, Breno Leitao wrote: > > > > Hello Andrey, > > > > On Mon, Nov 20, 2023 at 06:47:10PM +0100, andrey.konovalov@linux.dev wrote: > > > From: Andrey Konovalov > > > > > > Currently, stack depot uses the following locking scheme: > > > > > > 1. Lock-free accesses when looking up a stack record, which allows to > > > have multiple users to look up records in parallel; > > > 2. Spinlock for protecting the stack depot pools and the hash table > > > when adding a new record. > > > > > > For implementing the eviction of stack traces from stack depot, the > > > lock-free approach is not going to work anymore, as we will need to be > > > able to also remove records from the hash table. > > > > > > Convert the spinlock into a read/write lock, and drop the atomic accesses, > > > as they are no longer required. > > > > > > Looking up stack traces is now protected by the read lock and adding new > > > records - by the write lock. One of the following patches will add a new > > > function for evicting stack records, which will be protected by the write > > > lock as well. > > > > > > With this change, multiple users can still look up records in parallel. > > > > > > This is preparatory patch for implementing the eviction of stack records > > > from the stack depot. > > > > I am testing quite recent "debug" kernel (with KASAN, Lockdep, etc > > enabled). This kernel is based on > > 9f8413c4a66f2fb776d3dc3c9ed20bf435eb305e, and I found the following > > This version predates this series, as far as I can tell. Can you try linux-next? That is true. I will retest and let you know if it is still reproducible. Thanks.