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Wed, 26 Apr 2023 05:34:26 -0700 (PDT) Message-ID: <1ee0cfa0-c442-1e31-24a8-90dd8b7ab2a6@gmail.com> Date: Wed, 26 Apr 2023 20:34:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH 3/9] maple_tree: Modify the allocation method of mtree_alloc_range/rrange() To: "Liam R. Howlett" , Peng Zhang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org References: <20230425110511.11680-1-zhangpeng.00@bytedance.com> <20230425110511.11680-4-zhangpeng.00@bytedance.com> <20230425160815.mionpme7bmdequzb@revolver> From: Peng Zhang In-Reply-To: <20230425160815.mionpme7bmdequzb@revolver> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7D46310000D X-Rspam-User: X-Stat-Signature: eomot49334atpi8md1k7xoqop84uhqt8 X-HE-Tag: 1682512468-826756 X-HE-Meta: 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 SJ17OL2I 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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: 在 2023/4/26 00:08, Liam R. Howlett 写道: > * Peng Zhang [230425 07:05]: >> Let mtree_alloc_range() and mtree_alloc_rrange() use mas_empty_area() >> and mas_empty_area_rev() respectively for allocation to reduce code >> redundancy. And after doing this, we don't need to maintain two logically >> identical codes to improve maintainability. >> >> In fact, mtree_alloc_range/rrange() has some bugs. For example, when >> dealing with min equals to max (mas_empty_area/area_rev() has been fixed), >> the allocation will fail. >> There are still some other bugs in it, I saw it with my naked eyes, but >> I didn't test it, for example: >> When mtree_alloc_range()->mas_alloc()->mas_awalk(), we set mas.index = min, >> mas.last = max - size. However, mas_awalk() requires mas.index = min, >> mas.last = max, which may lead to allocation failures. > > Please don't re-state code in your commit messages. > > Try to focus on what you did, and not why. > > ie: Aligned mtree_alloc_range() to use the same internal function as > mas_empty_area(). > >> >> Right now no users are using these two functions so the bug won't trigger, >> but this might trigger in the future. >> >> Also use mas_store_gfp() instead of mas_fill_gap() as I don't see any >> difference between them. > > Yeah, evolution of the code converged on the same design. Thanks for > seeing this. > >> >> After doing this, we no longer need the three functions >> mas_fill_gap(), mas_alloc(), and mas_rev_alloc(). > > Let's just drop mtree_alloc_range() and mtree_alloc_rrange() and > whatever else you found here. They were planned to simplify the mmap > code allocations, but since there would need to be arch involvement > (coloring, etc) and alignment, etc; it is better to leave this job to > the mm code itself. Ok, I will remove some useless functions here. But mtree_alloc_range() and mtree_alloc_rrange() really don't need to be reserved? Because I don't know if there will be users using it in other scenarios in the future. Thank you for all your suggestions on this patch set, I will update them. > >> >> Fixes: 54a611b60590 ("Maple Tree: add new data structure") >> Signed-off-by: Peng Zhang >> --- >> lib/maple_tree.c | 45 ++++++++++++--------------------------------- >> 1 file changed, 12 insertions(+), 33 deletions(-) >> >> diff --git a/lib/maple_tree.c b/lib/maple_tree.c >> index aa55c914818a0..294d4c8668323 100644 >> --- a/lib/maple_tree.c >> +++ b/lib/maple_tree.c >> @@ -6362,32 +6362,20 @@ int mtree_alloc_range(struct maple_tree *mt, unsigned long *startp, >> { >> int ret = 0; >> >> - MA_STATE(mas, mt, min, max - size); >> + MA_STATE(mas, mt, 0, 0); >> if (!mt_is_alloc(mt)) >> return -EINVAL; >> >> if (WARN_ON_ONCE(mt_is_reserved(entry))) >> return -EINVAL; >> >> - if (min > max) >> - return -EINVAL; >> - >> - if (max < size) >> - return -EINVAL; >> - >> - if (!size) >> - return -EINVAL; >> - >> mtree_lock(mt); >> -retry: >> - mas.offset = 0; >> - mas.index = min; >> - mas.last = max - size; >> - ret = mas_alloc(&mas, entry, size, startp); >> - if (mas_nomem(&mas, gfp)) >> - goto retry; >> - >> + ret = mas_empty_area(&mas, min, max, size); >> + if (!ret) >> + ret = mas_store_gfp(&mas, entry, gfp); >> mtree_unlock(mt); >> + if (!ret) >> + *startp = mas.index; >> return ret; >> } >> EXPORT_SYMBOL(mtree_alloc_range); >> @@ -6398,29 +6386,20 @@ int mtree_alloc_rrange(struct maple_tree *mt, unsigned long *startp, >> { >> int ret = 0; >> >> - MA_STATE(mas, mt, min, max - size); >> + MA_STATE(mas, mt, 0, 0); >> if (!mt_is_alloc(mt)) >> return -EINVAL; >> >> if (WARN_ON_ONCE(mt_is_reserved(entry))) >> return -EINVAL; >> >> - if (min >= max) >> - return -EINVAL; >> - >> - if (max < size - 1) >> - return -EINVAL; >> - >> - if (!size) >> - return -EINVAL; >> - >> mtree_lock(mt); >> -retry: >> - ret = mas_rev_alloc(&mas, min, max, entry, size, startp); >> - if (mas_nomem(&mas, gfp)) >> - goto retry; >> - >> + ret = mas_empty_area_rev(&mas, min, max, size); >> + if (!ret) >> + ret = mas_store_gfp(&mas, entry, gfp); >> mtree_unlock(mt); >> + if (!ret) >> + *startp = mas.index; >> return ret; >> } >> EXPORT_SYMBOL(mtree_alloc_rrange); >> -- >> 2.20.1 >>