From: Chao Yu <yuchao0@huawei.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: don't return vmalloc() memory from f2fs_kmalloc()
Date: Thu, 7 May 2020 11:13:17 +0800 [thread overview]
Message-ID: <4e2b1c0f-292b-3a39-bcd2-06cc0680d3cd@huawei.com> (raw)
In-Reply-To: <20200506184301.GA842@sol.localdomain>
On 2020/5/7 2:43, Eric Biggers wrote:
> On Wed, May 06, 2020 at 03:43:36PM +0800, Chao Yu wrote:
>> On 2020/5/6 4:48, Eric Biggers wrote:
>>> From: Eric Biggers <ebiggers@google.com>
>>>
>>> kmalloc() returns kmalloc'ed memory, and kvmalloc() returns either
>>> kmalloc'ed or vmalloc'ed memory. But the f2fs wrappers, f2fs_kmalloc()
>>> and f2fs_kvmalloc(), both return both kinds of memory.
>>>
>>> It's redundant to have two functions that do the same thing, and also
>>> breaking the standard naming convention is causing bugs since people
>>> assume it's safe to kfree() memory allocated by f2fs_kmalloc(). See
>>> e.g. the various allocations in fs/f2fs/compress.c.
>>>
>>> Fix this by making f2fs_kmalloc() just use kmalloc(). And to avoid
>>> re-introducing the allocation failures that the vmalloc fallback was
>>> intended to fix, convert the largest allocations to use f2fs_kvmalloc().
>>
>> I've submitted one patch since you suggested when commented in compression
>> support patch.
>>
>> I remember Jaegeuk prefer to use f2fs_kvmalloc() to instead f2fs_kmalloc(),
>> and keep the order of kmalloc - failed - kvmalloc.
>>
>
> I think you're talking about
> https://lkml.kernel.org/r/20191105030451.GA55090@jaegeuk-macbookpro.roam.corp.google.com?
>
> I think that making the large allocations use kvmalloc(), as this patch does, is
> good enough to address any memory allocation failures that may have been
> encountered in the past. We don't need to switch all allocations to use
> kvmalloc(), as there's no benefit for small allocations.
Yeah, I agreed, and in ENOMEM case, small-sized kvmalloc increases allocating path
length unnecessarily.
Thanks,
>
> - Eric
> .
>
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next prev parent reply other threads:[~2020-05-07 3:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 20:48 [f2fs-dev] [PATCH] f2fs: don't return vmalloc() memory from f2fs_kmalloc() Eric Biggers
2020-05-06 7:43 ` Chao Yu
2020-05-06 18:43 ` Eric Biggers
2020-05-07 3:13 ` Chao Yu [this message]
2020-05-15 19:13 ` Eric Biggers
2020-05-18 18:06 ` Jaegeuk Kim
2020-05-18 18:35 ` Eric Biggers
2020-05-18 19:10 ` Jaegeuk Kim
2020-06-04 21:06 ` Eric Biggers
2020-06-05 1:15 ` Jaegeuk Kim
2020-06-05 4:56 ` Eric Biggers
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