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Tue, 31 Mar 2026 13:58:48 -0700 (PDT) MIME-Version: 1.0 References: <20260331183351.29844-1-kanchanapsridhar2026@gmail.com> In-Reply-To: From: "Kanchana P. Sridhar" Date: Tue, 31 Mar 2026 13:58:37 -0700 X-Gm-Features: AQROBzA9ZSoIDzkoZbPHpCipWylmpJkNBlGAZiNG_lJB22CqtR9m_YX0aEhKVXA Message-ID: Subject: Re: [PATCH v3 0/2] zswap pool per-CPU acomp_ctx simplifications To: Yosry Ahmed Cc: hannes@cmpxchg.org, nphamcs@gmail.com, chengming.zhou@linux.dev, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, herbert@gondor.apana.org.au, senozhatsky@chromium.org, "Kanchana P. Sridhar" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 7499F80010 X-Stat-Signature: 5ttb146n6to8k97nso1d6bei5f4n8i1w X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774990730-921381 X-HE-Meta: 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 as5vJ6QG 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 31, 2026 at 12:23=E2=80=AFPM Yosry Ahmed wro= te: > > On Tue, Mar 31, 2026 at 11:34=E2=80=AFAM Kanchana P. Sridhar > wrote: > > > > This patchset first removes redundant checks on the acomp_ctx and its > > "req" member in zswap_cpu_comp_dead(). > > > > Next, it persists the zswap pool's per-CPU acomp_ctx resources to > > last until the pool is destroyed. It then simplifies the per-CPU > > acomp_ctx mutex locking in zswap_compress()/zswap_decompress(). > > > > Code comments added after allocation and before checking to deallocate > > the per-CPU acomp_ctx's members, based on expected crypto API return > > values and zswap changes this patchset makes. > > > > Patch 2 is an independent submission of patch 23 from [1], to > > facilitate merging. > > > > [1]: https://patchwork.kernel.org/project/linux-mm/list/?series=3D10466= 77 > > > > Changes since v2: > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > 1) Rebased to mm-unstable as of 3-31-2026 (commit 24e341657c28). > > 2) Collected Acks. > > > > Changes since v1: > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > 1) Made the changes to eliminate redundant checks on > > acomp_ctx/acomp_ctx->req in zswap_cpu_comp_dead(), per Yosry. > > 2) Renamed acomp_ctx_dealloc() to acomp_ctx_free(), per Yosry. > > 3) Incorporated suggestions from Yosry and Sashiko to reset the > > acomp_ctx's members to NULL after freeing them, to prevent UAF and > > double free issues. > > 4) Replaced v1's patch 2 with v2's patch 1. > > > > > > Kanchana P. Sridhar (2): > > mm: zswap: Remove redundant checks in zswap_cpu_comp_dead(). > > mm: zswap: Tie per-CPU acomp_ctx lifetime to the pool. > > Sashiko was able to apply the patches and doesn't seem to find any > regressions: https://sashiko.dev/#/patchset/20260331183351.29844-1-kancha= napsridhar2026%40gmail.com. That's good to know, thanks for confirming Yosry!