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mm: allow multiple error returns in try_grab_page()

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In order to add checks for P2PDMA memory into try_grab_page(), expand
the error return from a bool to an int/error code. Update all the
callsites handle change in usage.

Also remove the WARN_ON_ONCE() call at the callsites seeing there
already is a WARN_ON_ONCE() inside the function if it fails.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221021174116.7200-2-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Logan Gunthorpe 2022-10-21 11:41:08 -06:00 committed by Jens Axboe
parent 5b2560c4c2
commit 0f0892356f
4 changed files with 37 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/mm.h
View File

@ -1129,7 +1129,7 @@ static inline void get_page(struct page *page)
folio_get(page_folio(page));
}
bool __must_check try_grab_page(struct page *page, unsigned int flags);
int __must_check try_grab_page(struct page *page, unsigned int flags);
static inline __must_check bool try_get_page(struct page *page)
{

26
mm/gup.c
View File

@ -202,17 +202,19 @@ static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
* time. Cases: please see the try_grab_folio() documentation, with
* "refs=1".
*
* Return: true for success, or if no action was required (if neither FOLL_PIN
* nor FOLL_GET was set, nothing is done). False for failure: FOLL_GET or
* FOLL_PIN was set, but the page could not be grabbed.
* Return: 0 for success, or if no action was required (if neither FOLL_PIN
* nor FOLL_GET was set, nothing is done). A negative error code for failure:
*
* -ENOMEM FOLL_GET or FOLL_PIN was set, but the page could not
* be grabbed.
*/
bool __must_check try_grab_page(struct page *page, unsigned int flags)
int __must_check try_grab_page(struct page *page, unsigned int flags)
{
struct folio *folio = page_folio(page);
WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));
if (WARN_ON_ONCE(folio_ref_count(folio) <= 0))
return false;
return -ENOMEM;
if (flags & FOLL_GET)
folio_ref_inc(folio);
@ -232,7 +234,7 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags)
node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1);
}
return true;
return 0;
}
/**
@ -624,8 +626,9 @@ retry:
!PageAnonExclusive(page), page);
/* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
if (unlikely(!try_grab_page(page, flags))) {
page = ERR_PTR(-ENOMEM);
ret = try_grab_page(page, flags);
if (unlikely(ret)) {
page = ERR_PTR(ret);
goto out;
}
/*
@ -960,10 +963,9 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
goto unmap;
*page = pte_page(*pte);
}
if (unlikely(!try_grab_page(*page, gup_flags))) {
ret = -ENOMEM;
ret = try_grab_page(*page, gup_flags);
if (unlikely(ret))
goto unmap;
}
out:
ret = 0;
unmap:
@ -2536,7 +2538,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
}
SetPageReferenced(page);
pages[*nr] = page;
if (unlikely(!try_grab_page(page, flags))) {
if (unlikely(try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
break;
}

19
mm/huge_memory.c
View File

@ -1035,6 +1035,7 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn = pmd_pfn(*pmd);
struct mm_struct *mm = vma->vm_mm;
struct page *page;
int ret;
assert_spin_locked(pmd_lockptr(mm, pmd));
@ -1066,8 +1067,9 @@ struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
if (!*pgmap)
return ERR_PTR(-EFAULT);
page = pfn_to_page(pfn);
if (!try_grab_page(page, flags))
page = ERR_PTR(-ENOMEM);
ret = try_grab_page(page, flags);
if (ret)
page = ERR_PTR(ret);
return page;
}
@ -1193,6 +1195,7 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn = pud_pfn(*pud);
struct mm_struct *mm = vma->vm_mm;
struct page *page;
int ret;
assert_spin_locked(pud_lockptr(mm, pud));
@ -1226,8 +1229,10 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
if (!*pgmap)
return ERR_PTR(-EFAULT);
page = pfn_to_page(pfn);
if (!try_grab_page(page, flags))
page = ERR_PTR(-ENOMEM);
ret = try_grab_page(page, flags);
if (ret)
page = ERR_PTR(ret);
return page;
}
@ -1435,6 +1440,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
{
struct mm_struct *mm = vma->vm_mm;
struct page *page;
int ret;
assert_spin_locked(pmd_lockptr(mm, pmd));
@ -1459,8 +1465,9 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
!PageAnonExclusive(page), page);
if (!try_grab_page(page, flags))
return ERR_PTR(-ENOMEM);
ret = try_grab_page(page, flags);
if (ret)
return ERR_PTR(ret);
if (flags & FOLL_TOUCH)
touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);

17
mm/hugetlb.c
View File

@ -7243,14 +7243,15 @@ retry:
page = pte_page(pte) +
((address & ~huge_page_mask(h)) >> PAGE_SHIFT);
/*
* try_grab_page() should always succeed here, because: a) we
* hold the pmd (ptl) lock, and b) we've just checked that the
* huge pmd (head) page is present in the page tables. The ptl
* prevents the head page and tail pages from being rearranged
* in any way. So this page must be available at this point,
* unless the page refcount overflowed:
* try_grab_page() should always be able to get the page here,
* because: a) we hold the pmd (ptl) lock, and b) we've just
* checked that the huge pmd (head) page is present in the
* page tables. The ptl prevents the head page and tail pages
* from being rearranged in any way. So this page must be
* available at this point, unless the page refcount
* overflowed:
*/
if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
if (try_grab_page(page, flags)) {
page = NULL;
goto out;
}
@ -7288,7 +7289,7 @@ retry:
pte = huge_ptep_get((pte_t *)pud);
if (pte_present(pte)) {
page = pud_page(*pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
if (WARN_ON_ONCE(!try_grab_page(page, flags))) {
if (try_grab_page(page, flags)) {
page = NULL;
goto out;
}