Ack On Fri, Aug 1, 2025 at 4:56 PM Liu Kui <kui....@virtuozzo.com> wrote: > > Fix page allocation failure in kcalloc by converting the large 1-dimensional > array into a 2-dimensional array of order-0 (4KB) pages. This eliminates the > need for non-order-0 allocations, improving allocation reliability under > memory > pressure. The 2D array ensures virtual contiguity for the caller maintaining > functional equivalence. > > Related to #VSTOR-112413 > https://virtuozzo.atlassian.net/browse/VSTOR-112413 > > Signed-off-by: Liu Kui <kui....@virtuozzo.com> > --- > fs/fuse/kio/pcs/pcs_mr.c | 55 +++++++++++++++++++++++++--------------- > fs/fuse/kio/pcs/pcs_mr.h | 21 ++++++++++----- > 2 files changed, 50 insertions(+), 26 deletions(-) > > diff --git a/fs/fuse/kio/pcs/pcs_mr.c b/fs/fuse/kio/pcs/pcs_mr.c > index cbd3b440dd1b..8e1dbc1121ce 100644 > --- a/fs/fuse/kio/pcs/pcs_mr.c > +++ b/fs/fuse/kio/pcs/pcs_mr.c > @@ -13,11 +13,18 @@ > void pcs_umem_release(struct pcs_umem *umem) > { > struct mm_struct *mm_s = umem->mm; > + int i, npages = umem->npages; > > - unpin_user_pages(umem->pages, umem->npages); > + for (i = 0; npages; i++) { > + int to_free = min_t(int, PCS_PAGES_PER_CHUNK, npages); > + > + unpin_user_pages(umem->page_chunk[i].pages, to_free); > + kfree(umem->page_chunk[i].pages); > + npages -= to_free; > + } > atomic64_sub(umem->npages, &mm_s->pinned_vm); > mmdrop(mm_s); > - kfree(umem->pages); > + kfree(umem->page_chunk); > kfree(umem); > } > > @@ -27,14 +34,13 @@ void pcs_umem_release(struct pcs_umem *umem) > struct pcs_umem *pcs_umem_get(u64 start, u64 len) > { > struct pcs_umem *umem = NULL; > - struct page **pages; > - int npages; > - u64 fp_va; > struct mm_struct *mm_s; > - int got, ret; > + u64 fp_va; > + int npages, nchunks, i, ret; > > fp_va = start & PAGE_MASK; > npages = PAGE_ALIGN(start + len - fp_va) >> PAGE_SHIFT; > + nchunks = (npages >> PCS_PAGE_CHUNK_SHIFT) + 1; > > umem = kzalloc(sizeof(*umem), GFP_KERNEL); > if (!umem) > @@ -48,25 +54,34 @@ struct pcs_umem *pcs_umem_get(u64 start, u64 len) > mmap_read_lock(mm_s); > > umem->fp_addr = fp_va; > - umem->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL); > - if (!umem->pages) { > + umem->page_chunk = kcalloc(nchunks, sizeof(struct pcs_page_chunk *), > GFP_KERNEL); > + if (!umem->page_chunk) { > ret = -ENOMEM; > goto out_err; > } > > - got = 0; > - while (npages) { > - pages = &umem->pages[got]; > - ret = pin_user_pages(fp_va, npages, FOLL_WRITE | > FOLL_LONGTERM, pages, NULL); > - if (ret < 0) > - goto out_err; > + for (i = 0; npages; i++) { > + int n = min_t(int, npages, PCS_PAGES_PER_CHUNK); > + struct page **pages = kcalloc(n, sizeof(struct page *), > GFP_KERNEL); > > - WARN_ON(ret == 0); > - umem->npages += ret; > - atomic64_add(ret, &mm_s->pinned_vm); > - fp_va += ret * PAGE_SIZE; > - npages -= ret; > - got += ret; > + if (!pages) { > + ret = -ENOMEM; > + goto out_err; > + } > + umem->page_chunk[i].pages = pages; > + > + while (n) { > + ret = pin_user_pages(fp_va, n, FOLL_WRITE | > FOLL_LONGTERM, pages, NULL); > + if (ret < 0) > + goto out_err; > + > + atomic64_add(ret, &mm_s->pinned_vm); > + umem->npages += ret; > + fp_va += ret * PAGE_SIZE; > + pages += ret; > + n -= ret; > + npages -= ret; > + } > } > mmap_read_unlock(mm_s); > > diff --git a/fs/fuse/kio/pcs/pcs_mr.h b/fs/fuse/kio/pcs/pcs_mr.h > index dae9931d9967..64f237f57dec 100644 > --- a/fs/fuse/kio/pcs/pcs_mr.h > +++ b/fs/fuse/kio/pcs/pcs_mr.h > @@ -11,6 +11,8 @@ > struct pcs_umem; > > #define PCS_MAX_MR 0x10000 > +#define PCS_PAGE_CHUNK_SHIFT 9 > +#define PCS_PAGES_PER_CHUNK (1 << PCS_PAGE_CHUNK_SHIFT) > > struct pcs_mr_set { > struct xarray mr_xa; /* array of registered MRs*/ > @@ -18,10 +20,15 @@ struct pcs_mr_set { > atomic_t mr_num; /* number of registered MRs*/ > }; > > +struct pcs_page_chunk > +{ > + struct page **pages; /* array of pinned pages */ > +}; > + > struct pcs_umem { > - u64 fp_addr; /* First page base address */ > - int npages; /* number of pinned pages */ > - struct page **pages; /* array of pinned pages */ > + struct pcs_page_chunk *page_chunk; > + int npages; /* number of pinned pages */ > + u64 fp_addr; /* First page base address */ > struct mm_struct *mm; /* mm the memory belongs to */ > }; > > @@ -40,10 +47,12 @@ struct pcs_mr { > */ > static inline struct page *pcs_umem_page(struct pcs_umem *umem, u64 addr) > { > - unsigned int idx = (addr - umem->fp_addr) >> PAGE_SHIFT; > + unsigned int page_idx = (addr - umem->fp_addr) >> PAGE_SHIFT; > + unsigned int chunk_idx = page_idx >> PCS_PAGE_CHUNK_SHIFT; > + unsigned int page_in_chunk = page_idx & (PCS_PAGES_PER_CHUNK - 1); > > - if (likely(idx < umem->npages)) > - return umem->pages[idx]; > + if (likely(page_idx < umem->npages)) > + return umem->page_chunk[chunk_idx].pages[page_in_chunk]; > return NULL; > } > > -- > 2.39.5 (Apple Git-154)
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