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shmem: move memcg charge out of shmem_add_to_page_cache() 

Extract shmem's memcg charging out of shmem_add_to_page_cache(): it's
misleading done there, because many calls are dealing with a swapcache
page, whose memcg is nowadays always remembered while swapped out, then
the charge re-levied when it's brought back into swapcache.

Temporarily move it back up to the shmem_get_folio_gfp() level, where the
memcg was charged before v5.8; but the next commit goes on to move it back
down to a new home.

In making this change, it becomes clear that shmem_swapin_folio() does not
need to know the vma, just the fault mm (if any): call it fault_mm rather
than charge_mm - let mem_cgroup_charge() decide whom to charge.

Link: https://lkml.kernel.org/r/4b2143c5-bf32-64f0-841-81a81158dac@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Carlos Maiolino <cem@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2023-09-29 20:31:27 -07:00 committed by Andrew Morton
parent 4199f51a7e
commit 054a9f7ccd
1 changed files with 29 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
mm/shmem.c
View File

@ -146,9 +146,8 @@ static unsigned long shmem_default_max_inodes(void)
#endif
static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
struct folio **foliop, enum sgp_type sgp,
gfp_t gfp, struct vm_area_struct *vma,
vm_fault_t *fault_type);
struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
struct mm_struct *fault_mm, vm_fault_t *fault_type);
static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
{
@ -760,12 +759,10 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
*/
static int shmem_add_to_page_cache(struct folio *folio,
struct address_space *mapping,
pgoff_t index, void *expected, gfp_t gfp,
struct mm_struct *charge_mm)
pgoff_t index, void *expected, gfp_t gfp)
{
XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
long nr = folio_nr_pages(folio);
int error;
VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
@ -776,16 +773,7 @@ static int shmem_add_to_page_cache(struct folio *folio,
folio->mapping = mapping;
folio->index = index;
if (!folio_test_swapcache(folio)) {
error = mem_cgroup_charge(folio, charge_mm, gfp);
if (error) {
if (folio_test_pmd_mappable(folio)) {
count_vm_event(THP_FILE_FALLBACK);
count_vm_event(THP_FILE_FALLBACK_CHARGE);
}
goto error;
}
}
gfp &= GFP_RECLAIM_MASK;
folio_throttle_swaprate(folio, gfp);
do {
@ -813,15 +801,12 @@ unlock:
} while (xas_nomem(&xas, gfp));
if (xas_error(&xas)) {
error = xas_error(&xas);
goto error;
folio->mapping = NULL;
folio_ref_sub(folio, nr);
return xas_error(&xas);
}
return 0;
error:
folio->mapping = NULL;
folio_ref_sub(folio, nr);
return error;
}
/*
@ -1324,10 +1309,8 @@ static int shmem_unuse_swap_entries(struct inode *inode,
if (!xa_is_value(folio))
continue;
error = shmem_swapin_folio(inode, indices[i],
&folio, SGP_CACHE,
mapping_gfp_mask(mapping),
NULL, NULL);
error = shmem_swapin_folio(inode, indices[i], &folio, SGP_CACHE,
mapping_gfp_mask(mapping), NULL, NULL);
if (error == 0) {
folio_unlock(folio);
folio_put(folio);
@ -1810,12 +1793,11 @@ static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
*/
static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
struct folio **foliop, enum sgp_type sgp,
gfp_t gfp, struct vm_area_struct *vma,
gfp_t gfp, struct mm_struct *fault_mm,
vm_fault_t *fault_type)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
struct swap_info_struct *si;
struct folio *folio = NULL;
swp_entry_t swap;
@ -1843,7 +1825,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
if (fault_type) {
*fault_type |= VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
count_memcg_event_mm(charge_mm, PGMAJFAULT);
count_memcg_event_mm(fault_mm, PGMAJFAULT);
}
/* Here we actually start the io */
folio = shmem_swapin(swap, gfp, info, index);
@ -1880,8 +1862,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
}
error = shmem_add_to_page_cache(folio, mapping, index,
swp_to_radix_entry(swap), gfp,
charge_mm);
swp_to_radix_entry(swap), gfp);
if (error)
goto failed;
@ -1929,7 +1910,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_sb_info *sbinfo;
struct mm_struct *charge_mm;
struct mm_struct *fault_mm;
struct folio *folio;
pgoff_t hindex;
gfp_t huge_gfp;
@ -1946,7 +1927,7 @@ repeat:
}
sbinfo = SHMEM_SB(inode->i_sb);
charge_mm = vma ? vma->vm_mm : NULL;
fault_mm = vma ? vma->vm_mm : NULL;
folio = filemap_get_entry(mapping, index);
if (folio && vma && userfaultfd_minor(vma)) {
@ -1958,7 +1939,7 @@ repeat:
if (xa_is_value(folio)) {
error = shmem_swapin_folio(inode, index, &folio,
sgp, gfp, vma, fault_type);
sgp, gfp, fault_mm, fault_type);
if (error == -EEXIST)
goto repeat;
@ -2044,9 +2025,16 @@ alloc_nohuge:
if (sgp == SGP_WRITE)
__folio_set_referenced(folio);
error = shmem_add_to_page_cache(folio, mapping, hindex,
NULL, gfp & GFP_RECLAIM_MASK,
charge_mm);
error = mem_cgroup_charge(folio, fault_mm, gfp);
if (error) {
if (folio_test_pmd_mappable(folio)) {
count_vm_event(THP_FILE_FALLBACK);
count_vm_event(THP_FILE_FALLBACK_CHARGE);
}
goto unacct;
}
error = shmem_add_to_page_cache(folio, mapping, hindex, NULL, gfp);
if (error)
goto unacct;
@ -2644,8 +2632,10 @@ int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
if (unlikely(pgoff >= max_off))
goto out_release;
ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL,
gfp & GFP_RECLAIM_MASK, dst_vma->vm_mm);
ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
if (ret)
goto out_release;
ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
if (ret)
goto out_release;