From nobody Sun Feb 8 20:34:11 2026 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE60F17E9 for ; Sat, 16 Mar 2024 01:58:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710554288; cv=none; b=mKyWgcmLdwUHHQR73Bj5rV79pIT4BJT+LWDO4QlDWKkW0Pihe3XvpM/wYufqBc8ZimwWJAaA4ko+OWVe5pqGAgdzyaO3QyjjHBRLIaVdFz/sI1JtGtRxgG0XfvwxPzp10svhGp9liJyeO5ugrsBmDd3t/yCCdQ84qR+Nz16QCz8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710554288; c=relaxed/simple; bh=aUUK1f7m/VOQ2n5+Z0YNpJ/VO1faVhBvtbBDCJbp2JY=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=glu0V1T056uio4H0ZRj3mlJ79cu2FS+xAs+82x/rk4lcmX5RqRqaJ4XK0iWiG4aWvYDuiK7wF+CaPR33TYZUv/rRuMjP9djvjloQ4BfC+p27ZvUGpQ2dkgneaSvko36KEqFFGv0abtHHndS6uRidJZ4R8NPyuHBXHib7OlrzOrk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--yosryahmed.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=WuOmhsgu; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--yosryahmed.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WuOmhsgu" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-60a629e2121so48433427b3.0 for ; Fri, 15 Mar 2024 18:58:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1710554286; x=1711159086; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=nz/rmcCjj7pCrgBiVdioT3UkYrnHawa2JdhbUXSYaXE=; b=WuOmhsgukkj9RPHyfSej1xNUhg1zvlD/9BbWqpJp94AA/XwczxoaRs9M1JfX7c5U5x l6V+pENvwT4m0vpc7pfLHYBg+KsAqtdlTVBEM27LZFAb+AfZXyTHMTOx4BHseHwNtsEJ wgFdU4/lFRi1xpTNqyNYMPJ0vOFm4k5XNOe1P9detQqWKbKsp17Mpdq4GO4C8a4OAwsF sqElxKl5ZPEePxa6nLqN+ik9f5lfJaudgX9fifkV9UvxPoehUMztQKQNbl4IPF9ZdiQP qa/RlHez9bFUN4lad3PWzt2221PLwmI4D8TWhVIIK847Ayo25Lv8P7EC8jRFh9OBF1HP A1uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710554286; x=1711159086; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=nz/rmcCjj7pCrgBiVdioT3UkYrnHawa2JdhbUXSYaXE=; b=YpnM/uqGGgiAVq90JAuOzA5VgQTYPVOVjyckrgwNzVU32WoSiojve/W6bBV6nVfleq L7OoG4SItwKIzNPDIMGWq2qyQfpvLOQH3QdxDwwLFtqVvxjBrApgpfym4ikBDTEfsngE HJ5kbrDmlgFHjWkDKrbW10h3oN7caW3CYuLH+4aYqh3ZfByGzxc2Sr/f6P3JRYXC+cff Tlf8ecljQmywDqHGGkkE/sSpSWvl0UOruvHplKmTtPGTunvU2fSuWSyrVJMGX9M73kno jU+fLN0mNgDLtttSqfmI31k1SC2il3adPf9+qaO7seMPSPy0oYJB3p0Y9se8BTUnkLHv 3bHA== X-Forwarded-Encrypted: i=1; AJvYcCWE4tY45/2MPUALgFIi1Rn744Ksi0B/VTEB0PR8NZVthJJVHK++0/uUSVz+X9n1dMYmIMW83Bb8i4RZcQw8ENM7o6568HOZALJ9khFn X-Gm-Message-State: AOJu0Yydi9RF36daqAy50sjiysU+YZsvfBWYZLQfNkS4pc0IfZPCxu3Q dtJlL95C35IApVrC/vgeVmZx5dmeTxielR0pkjLgvlYw9dpLLUTfc29S6T+r10pSYgpgi7yA+m7 m51b00uVEFKSW6fTW5g== X-Google-Smtp-Source: AGHT+IGmRUBmhZYJ4tRjAVcL7DY6ga9tWCPr/y80MXCGP3YTBlk6hr1HiyCUa9cZ20xmmsx/xGgByCG91hqdia4A X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:29b4]) (user=yosryahmed job=sendgmr) by 2002:a0d:e813:0:b0:609:25d1:ea9a with SMTP id r19-20020a0de813000000b0060925d1ea9amr1600283ywe.9.1710554285742; Fri, 15 Mar 2024 18:58:05 -0700 (PDT) Date: Sat, 16 Mar 2024 01:58:03 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.44.0.291.gc1ea87d7ee-goog Message-ID: <20240316015803.2777252-1-yosryahmed@google.com> Subject: [PATCH] mm: memcg: add NULL check to obj_cgroup_put() From: Yosry Ahmed To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yosry Ahmed Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 9 out of 16 callers perform a NULL check before calling obj_cgroup_put(). Move the NULL check in the function, similar to mem_cgroup_put(). The unlikely() NULL check in current_objcg_update() was left alone to avoid dropping the unlikey() annotation as this a fast path. Signed-off-by: Yosry Ahmed Acked-by: Johannes Weiner Acked-by: Roman Gushchin --- include/linux/memcontrol.h | 3 ++- kernel/bpf/memalloc.c | 6 ++---- mm/memcontrol.c | 18 ++++++------------ mm/zswap.c | 3 +-- 4 files changed, 11 insertions(+), 19 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 394fd0a887ae7..b6264796815d4 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -818,7 +818,8 @@ static inline void obj_cgroup_get_many(struct obj_cgrou= p *objcg, =20 static inline void obj_cgroup_put(struct obj_cgroup *objcg) { - percpu_ref_put(&objcg->refcnt); + if (objcg) + percpu_ref_put(&objcg->refcnt); } =20 static inline bool mem_cgroup_tryget(struct mem_cgroup *memcg) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 550f02e2cb132..a546aba46d5da 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -759,8 +759,7 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) rcu_in_progress +=3D atomic_read(&c->call_rcu_ttrace_in_progress); rcu_in_progress +=3D atomic_read(&c->call_rcu_in_progress); } - if (ma->objcg) - obj_cgroup_put(ma->objcg); + obj_cgroup_put(ma->objcg); destroy_mem_alloc(ma, rcu_in_progress); } if (ma->caches) { @@ -776,8 +775,7 @@ void bpf_mem_alloc_destroy(struct bpf_mem_alloc *ma) rcu_in_progress +=3D atomic_read(&c->call_rcu_in_progress); } } - if (ma->objcg) - obj_cgroup_put(ma->objcg); + obj_cgroup_put(ma->objcg); destroy_mem_alloc(ma, rcu_in_progress); } } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 138bcfa182344..aab3f5473203a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2370,8 +2370,7 @@ static void drain_local_stock(struct work_struct *dum= my) clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); =20 local_unlock_irqrestore(&memcg_stock.stock_lock, flags); - if (old) - obj_cgroup_put(old); + obj_cgroup_put(old); } =20 /* @@ -3147,8 +3146,7 @@ static struct obj_cgroup *current_objcg_update(void) if (old) { old =3D (struct obj_cgroup *) ((unsigned long)old & ~CURRENT_OBJCG_UPDATE_FLAG); - if (old) - obj_cgroup_put(old); + obj_cgroup_put(old); =20 old =3D NULL; } @@ -3420,8 +3418,7 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct= pglist_data *pgdat, mod_objcg_mlstate(objcg, pgdat, idx, nr); =20 local_unlock_irqrestore(&memcg_stock.stock_lock, flags); - if (old) - obj_cgroup_put(old); + obj_cgroup_put(old); } =20 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_by= tes) @@ -3548,8 +3545,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg= , unsigned int nr_bytes, } =20 local_unlock_irqrestore(&memcg_stock.stock_lock, flags); - if (old) - obj_cgroup_put(old); + obj_cgroup_put(old); =20 if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages); @@ -5470,8 +5466,7 @@ static void __mem_cgroup_free(struct mem_cgroup *memc= g) { int node; =20 - if (memcg->orig_objcg) - obj_cgroup_put(memcg->orig_objcg); + obj_cgroup_put(memcg->orig_objcg); =20 for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); @@ -6622,8 +6617,7 @@ static void mem_cgroup_exit(struct task_struct *task) =20 objcg =3D (struct obj_cgroup *) ((unsigned long)objcg & ~CURRENT_OBJCG_UPDATE_FLAG); - if (objcg) - obj_cgroup_put(objcg); + obj_cgroup_put(objcg); =20 /* * Some kernel allocations can happen after this point, diff --git a/mm/zswap.c b/mm/zswap.c index e0ec91995f4e3..3c2f960a789ba 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1533,8 +1533,7 @@ bool zswap_store(struct folio *folio) freepage: zswap_entry_cache_free(entry); reject: - if (objcg) - obj_cgroup_put(objcg); + obj_cgroup_put(objcg); check_old: /* * If the zswap store fails or zswap is disabled, we must invalidate the --=20 2.44.0.291.gc1ea87d7ee-goog