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AJvYcCXXC6/gTbqXukFXZGmtJepi36a9zHo5ZkZCsUUzRHaUFdEGAM2CS6BfwbzOW3DDndVEiWZ3oBmtVg==@kvack.org X-Gm-Message-State: AOJu0YyvYeq54FlpAf06j3wi6vJgsJO+2z26BbxdeiBIP48GOQVHTytu 340oJz0csvCn0qy93ZYRcLE911dXTmpCY9VQl/P9IvYorDBbDp9Z X-Google-Smtp-Source: AGHT+IHoEIbFIJ2FJVnH1egn2UyEN4ORAxEtM1IFsFqxRQHHSDaXGTAKzmOvWILacGIaqQ3mQ00qqw== X-Received: by 2002:a17:907:d3d8:b0:a8d:4e26:c9b9 with SMTP id a640c23a62f3a-a99b9583165mr62411466b.17.1728610047900; Thu, 10 Oct 2024 18:27:27 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a99a7ec54c1sm156181866b.10.2024.10.10.18.27.25 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 10 Oct 2024 18:27:27 -0700 (PDT) Date: Fri, 11 Oct 2024 01:27:25 +0000 From: Wei Yang To: Wei Yang Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, maple-tree@lists.infradead.org, linux-mm@kvack.org, Sidhartha Kumar Subject: Re: [PATCH 4/4] maple_tree: fix potential allocation failure even has memory Message-ID: <20241011012725.ffof6uh4huffz73q@master> Reply-To: Wei Yang References: <20240924123954.18933-1-richard.weiyang@gmail.com> <20240924123954.18933-5-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240924123954.18933-5-richard.weiyang@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 87367C000C X-Stat-Signature: g3qdge5n7twe3s4j834z8q4h1uwa3oth X-Rspam-User: X-HE-Tag: 1728610048-513803 X-HE-Meta: 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 e2cSQn15 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 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: Related fix has been posted, but not merged yet. lkml.kernel.org/r/20240626160631.3636515-1-Liam.Howlett@oracle.com May drop this one. On Tue, Sep 24, 2024 at 12:39:54PM +0000, Wei Yang wrote: >We got an rare case when mas_node_count() would fail even there is >enough memory. > >The reason is the maple_alloc grows downward. And when hit a full >maple_alloc, the max_req would be 0. This leads to mt_alloc_bulk() >return 0, which means failure here. > >For example, here is the test code: > > expect = MAPLE_ALLOC_SLOTS + 1; > mas_node_count(&ms, expect); > pr_info("expect %d allocated %lu\n", expect, mas_allocated(&ms)); > expect = MAPLE_ALLOC_SLOTS * 2 + 2; > mas_node_count(&ms, expect); > pr_info("expect %d allocated %lu\n", expect, mas_allocated(&ms)); > >We will get the following output, which shows we fail to allocate the >required number of nodes. > > expect 31 allocated 31 > expect 62 allocated 61 > >The straight forward way to fix it is go down one level more. > >Signed-off-by: Wei Yang >CC: Liam R. Howlett >CC: Sidhartha Kumar >--- > lib/maple_tree.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > >diff --git a/lib/maple_tree.c b/lib/maple_tree.c >index 1cbc5f7ca40d..dd33d0793dd1 100644 >--- a/lib/maple_tree.c >+++ b/lib/maple_tree.c >@@ -1253,8 +1253,10 @@ static inline void mas_alloc_nodes(struct ma_state *mas, gfp_t gfp) > } > > node = mas->alloc; >- while (requested) { >+ for (; requested; node = node->slot[0]) { > max_req = MAPLE_ALLOC_SLOTS - node->node_count; >+ if (unlikely(!max_req)) >+ continue; > slots = (void **)&node->slot[node->node_count]; > max_req = min(requested, max_req); > count = mt_alloc_bulk(gfp, max_req, slots); >@@ -1268,7 +1270,6 @@ static inline void mas_alloc_nodes(struct ma_state *mas, gfp_t gfp) > > node->node_count += count; > allocated += count; >- node = node->slot[0]; > requested -= count; > } > mas->alloc->total = allocated; >-- >2.34.1 -- Wei Yang Help you, Help me