The patch titled
Subject: drivers/IB,hfi1: do not se mmap_sem
has been added to the -mm tree. Its filename is
drivers-ibhfi1-do-not-se-mmap_sem.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/drivers-ibhfi1-do-not-se-mmap_sem.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/drivers-ibhfi1-do-not-se-mmap_sem.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: drivers/IB,hfi1: do not se mmap_sem
This driver already uses gup_fast() and thus we can just drop the mmap_sem
protection around the pinned_vm counter. Note that the window between
when hfi1_can_pin_pages() is called and the actual counter is incremented
remains the same as mmap_sem was _only_ used for when ->pinned_vm was
touched.
Link: http://lkml.kernel.org/r/20190206175920.31082-5-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/drivers/infiniband/hw/hfi1/user_pages.c~drivers-ibhfi1-do-not-se-mmap_sem
+++ a/drivers/infiniband/hw/hfi1/user_pages.c
@@ -91,9 +91,7 @@ bool hfi1_can_pin_pages(struct hfi1_devd
/* Convert to number of pages */
size = DIV_ROUND_UP(size, PAGE_SIZE);
- down_read(&mm->mmap_sem);
pinned = atomic64_read(&mm->pinned_vm);
- up_read(&mm->mmap_sem);
/* First, check the absolute limit against all pinned pages. */
if (pinned + npages >= ulimit && !can_lock)
@@ -111,9 +109,7 @@ int hfi1_acquire_user_pages(struct mm_st
if (ret < 0)
return ret;
- down_write(&mm->mmap_sem);
atomic64_add(ret, &mm->pinned_vm);
- up_write(&mm->mmap_sem);
return ret;
}
@@ -130,8 +126,6 @@ void hfi1_release_user_pages(struct mm_s
}
if (mm) { /* during close after signal, mm can be NULL */
- down_write(&mm->mmap_sem);
atomic64_sub(npages, &mm->pinned_vm);
- up_write(&mm->mmap_sem);
}
}
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
mm-make-mm-pinned_vm-an-atomic64-counter.patch
drivers-mic-scif-do-not-use-mmap_sem.patch
drivers-ibqib-optimize-mmap_sem-usage.patch
drivers-ibhfi1-do-not-se-mmap_sem.patch
drivers-ibusnic-reduce-scope-of-mmap_sem.patch
drivers-ibcore-reduce-scope-of-mmap_sem.patch
