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AJvYcCVG17Eta5+fHdb0QyPN1RXmkZFOhyCdpA8sP+D37wHqlSZt8ozVWc49mwKWKjClGpUKB0QxQuvyCw==@kvack.org X-Gm-Message-State: AOJu0Yzj3ZHQ/TVWdu6CoMq8XXpb2GFLf/SGcUCn3WEq/RFXZV42+HGY DDY1/I75FbCDWmswKt+bPDaryKJVarUVtbW+ZQh8xfuMJDI/Ja5pQSNVs3uuxBuulIQ09yhqK11 KzdZCnrI4uPgRQG1dPv3SRsXcEpw= X-Gm-Gg: ASbGnctYeSTBmAwg6O9/RrWkwxTQkivyFZfe2+pTWV6d+f6HnszvDHEusdmC8yrOFWI Y/p8Z1u59oFWcXw2HG5uiVLnBFsD9YNbIU0ee3lxIq3p2MXjjjAL1G7OJ+IQtq1qBVl+xvpk= X-Google-Smtp-Source: AGHT+IFGDjr0bCmLrrvx1f8jxTqNF0S5/R2+I3JIAkozSnMNxDI++ym7dXk8Hku9koAZrhrlIK4yLeFMuaeCptMlrCE= X-Received: by 2002:a05:6402:50d3:b0:5dc:1239:1e40 with SMTP id 4fb4d7f45d1cf-5dc5f00851bmr22854933a12.31.1738611200300; Mon, 03 Feb 2025 11:33:20 -0800 (PST) MIME-Version: 1.0 References: <20250201163106.28912-1-mjguzik@gmail.com> <20250201163106.28912-4-mjguzik@gmail.com> <20250203180623.GC1003@redhat.com> In-Reply-To: <20250203180623.GC1003@redhat.com> From: Mateusz Guzik Date: Mon, 3 Feb 2025 20:33:07 +0100 X-Gm-Features: AWEUYZmEPqQjEvfptjb7WFQmVt-nVfYjwqmar3M5fFEh1pCYK8pa6ALc_W9oFl0 Message-ID: Subject: Re: [PATCH v3 3/6] exit: postpone tty_kref_put() until after tasklist_lock is dropped To: Oleg Nesterov Cc: ebiederm@xmission.com, brauner@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: EC706140013 X-Stat-Signature: fbwxrn7yzegsc9b5hkd5uq5ffijyj9w1 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1738611201-649806 X-HE-Meta: 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 Hd+SH6Fl Pj1Sdf19nMUeE0enhZin6imKpX3X7QGGFt95EroJJx0UGRJhPdFRMkzV1Vk0jK2STvgg7iKMrY+eMOJATKxDfZaH4a29yQFSrdRSb2QkEIcGy7/SdQ6SOWr1yd2vKbKw7TWA+3D6b+QmeLQx2k4risZ1KnwsEQqj3E/r5/w6TQ3TDjgZef1PzMBNc4TpEvgj+GUUgzfpokU2jCqDZetYbJS1FoNdDhTJZjPPVbgouvixRsPXZ8bVbyV2bx+b066jX/vPVva2WmR+1raSJM2vYNAPsjJR1Zqt3i1vNvgqGOCyfE3HrQ4mr4nxJVNH/eyBm2BQEHl0OgJ24MWmBciJssgQehF+pcM/ruiZ3n5+9DalkhAWceVNCF+FnIm0JImOlK09F+PVy49PKU7SY62kiOv0WzAwjBf+Tzcml X-Bogosity: Ham, tests=bogofilter, spamicity=0.007256, 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 Mon, Feb 3, 2025 at 7:07=E2=80=AFPM Oleg Nesterov wrot= e: > > On 02/01, Mateusz Guzik wrote: > > > > Instead of smuggling the tty pointer directly, use a struct so that mor= e > > things can be added later. > > I am not sure this particular change worth the effort, but I won't argue. > I'd like to know what Eric thinks. > it trivially whacks an atomic from an area protected by a global lock > OTOH, if we do this, then perhaps we can do more "call tty_kref_put() > lockless" changes later. And perhaps even add the new > > void tty_kref_put_sync(struct tty_struct *tty) > { > if (tty) > kref_put(&tty->kref, release_one_tty); > } > > helper. With this change release_task() doesn't need to abuse > schedule_work(), and this helper can have more users. > > Nevermind, this is almost off-topic. > I have no interest in messing with ttys, regardless I agree this is definitely something to consider *after* this patch is sorted out. --=20 Mateusz Guzik