[PATCH v2] cma_alloc(), indefinitely retry allocations for -EBUSY failures
On mobile devices, failure to allocate from a CMA area constitutes a
functional failure. Sometimes during CMA allocations, we have observed
that pages in a CMA area allocated through alloc_pages(), that we're trying
to migrate away to make room for a CMA allocation, are temporarily pinned.
This temporary pinning can occur when a process that owns the pinned page
is being forked (the example is explained further in the commit text), or it is
exiting. This patch addresses this issue by indefinitely retrying allocations
that fail due to a return of -EBUSY.
** This change log was re-sent due to threading issues **
Change log:
v1: We were performing retries of the allocation a fixed number of times.
Andrew Morton disliked this, as it didn't guarantee that the allocation would
succeed.
https://lkml.org/lkml/2020/8/5/1096
https://lkml.org/lkml/2020/8/21/1490
v2: To address this concern, we switched to retrying indefinitely, as opposed to
doing to retrying the allocation a limited number of times.
Chris Goldsworthy (1):
mm: cma: indefinitely retry allocations in cma_alloc
mm/cma.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On 2020-09-11 13:54, Chris Goldsworthy wrote:
> [PATCH v2] cma_alloc(), indefinitely retry allocations for -EBUSY
> failures
>
> On mobile devices, failure to allocate from a CMA area constitutes a
> functional failure. Sometimes during CMA allocations, we have observed
> that pages in a CMA area allocated through alloc_pages(), that we're
> trying
> to migrate away to make room for a CMA allocation, are temporarily
> pinned.
> This temporary pinning can occur when a process that owns the pinned
> page
> is being forked (the example is explained further in the commit text),
> or it is
> exiting. This patch addresses this issue by indefinitely retrying
> allocations
> that fail due to a return of -EBUSY.
>
> ** This change log was re-sent due to threading issues **
>
> Change log:
>
> v1: We were performing retries of the allocation a fixed number of
> times.
> Andrew Morton disliked this, as it didn't guarantee that the allocation
> would
> succeed.
>
> https://lkml.org/lkml/2020/8/5/1096
> https://lkml.org/lkml/2020/8/21/1490
>
> v2: To address this concern, we switched to retrying indefinitely, as
> opposed to
> doing to retrying the allocation a limited number of times.
>
> Chris Goldsworthy (1):
> mm: cma: indefinitely retry allocations in cma_alloc
>
> mm/cma.c | 25 +++++++++++++++++++++++--
> 1 file changed, 23 insertions(+), 2 deletions(-)
test
--
The Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
a Linux Foundation Collaborative Project