From f8f9ee479439c1be9e33c4404912a2a112c46200 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 26 Aug 2019 12:08:39 -0700 Subject: [PATCH] xfs: add kmem_alloc_io() Memory we use to submit for IO needs strict alignment to the underlying driver contraints. Worst case, this is 512 bytes. Given that all allocations for IO are always a power of 2 multiple of 512 bytes, the kernel heap provides natural alignment for objects of these sizes and that suffices. Until, of course, memory debugging of some kind is turned on (e.g. red zones, poisoning, KASAN) and then the alignment of the heap objects is thrown out the window. Then we get weird IO errors and data corruption problems because drivers don't validate alignment and do the wrong thing when passed unaligned memory buffers in bios. TO fix this, introduce kmem_alloc_io(), which will guaranteeat least 512 byte alignment of buffers for IO, even if memory debugging options are turned on. It is assumed that the minimum allocation size will be 512 bytes, and that sizes will be power of 2 mulitples of 512 bytes. Use this everywhere we allocate buffers for IO. This no longer fails with log recovery errors when KASAN is enabled due to the brd driver not handling unaligned memory buffers: # mkfs.xfs -f /dev/ram0 ; mount /dev/ram0 /mnt/test Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/kmem.c | 66 +++++++++++++++++++++++++++++----------- fs/xfs/kmem.h | 1 + fs/xfs/xfs_buf.c | 5 +-- fs/xfs/xfs_log.c | 5 +-- fs/xfs/xfs_log_recover.c | 4 ++- fs/xfs/xfs_trace.h | 1 + 6 files changed, 60 insertions(+), 22 deletions(-) diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c index 9f32af534ce4..da031b93e182 100644 --- a/fs/xfs/kmem.c +++ b/fs/xfs/kmem.c @@ -30,30 +30,24 @@ kmem_alloc(size_t size, xfs_km_flags_t flags) } while (1); } -void * -kmem_alloc_large(size_t size, xfs_km_flags_t flags) + +/* + * __vmalloc() will allocate data pages and auxillary structures (e.g. + * pagetables) with GFP_KERNEL, yet we may be under GFP_NOFS context here. Hence + * we need to tell memory reclaim that we are in such a context via + * PF_MEMALLOC_NOFS to prevent memory reclaim re-entering the filesystem here + * and potentially deadlocking. + */ +static void * +__kmem_vmalloc(size_t size, xfs_km_flags_t flags) { unsigned nofs_flag = 0; void *ptr; - gfp_t lflags; + gfp_t lflags = kmem_flags_convert(flags); - trace_kmem_alloc_large(size, flags, _RET_IP_); - - ptr = kmem_alloc(size, flags | KM_MAYFAIL); - if (ptr) - return ptr; - - /* - * __vmalloc() will allocate data pages and auxillary structures (e.g. - * pagetables) with GFP_KERNEL, yet we may be under GFP_NOFS context - * here. Hence we need to tell memory reclaim that we are in such a - * context via PF_MEMALLOC_NOFS to prevent memory reclaim re-entering - * the filesystem here and potentially deadlocking. - */ if (flags & KM_NOFS) nofs_flag = memalloc_nofs_save(); - lflags = kmem_flags_convert(flags); ptr = __vmalloc(size, lflags, PAGE_KERNEL); if (flags & KM_NOFS) @@ -62,6 +56,44 @@ kmem_alloc_large(size_t size, xfs_km_flags_t flags) return ptr; } +/* + * Same as kmem_alloc_large, except we guarantee the buffer returned is aligned + * to the @align_mask. We only guarantee alignment up to page size, we'll clamp + * alignment at page size if it is larger. vmalloc always returns a PAGE_SIZE + * aligned region. + */ +void * +kmem_alloc_io(size_t size, int align_mask, xfs_km_flags_t flags) +{ + void *ptr; + + trace_kmem_alloc_io(size, flags, _RET_IP_); + + if (WARN_ON_ONCE(align_mask >= PAGE_SIZE)) + align_mask = PAGE_SIZE - 1; + + ptr = kmem_alloc(size, flags | KM_MAYFAIL); + if (ptr) { + if (!((uintptr_t)ptr & align_mask)) + return ptr; + kfree(ptr); + } + return __kmem_vmalloc(size, flags); +} + +void * +kmem_alloc_large(size_t size, xfs_km_flags_t flags) +{ + void *ptr; + + trace_kmem_alloc_large(size, flags, _RET_IP_); + + ptr = kmem_alloc(size, flags | KM_MAYFAIL); + if (ptr) + return ptr; + return __kmem_vmalloc(size, flags); +} + void * kmem_realloc(const void *old, size_t newsize, xfs_km_flags_t flags) { diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h index cb6fa7984ffa..8170d95cf930 100644 --- a/fs/xfs/kmem.h +++ b/fs/xfs/kmem.h @@ -53,6 +53,7 @@ kmem_flags_convert(xfs_km_flags_t flags) } extern void *kmem_alloc(size_t, xfs_km_flags_t); +extern void *kmem_alloc_io(size_t size, int align_mask, xfs_km_flags_t flags); extern void *kmem_alloc_large(size_t size, xfs_km_flags_t); extern void *kmem_realloc(const void *, size_t, xfs_km_flags_t); static inline void kmem_free(const void *ptr) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index d3be9ab0359b..120ef99d09e8 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -353,7 +353,8 @@ xfs_buf_allocate_memory( */ size = BBTOB(bp->b_length); if (size < PAGE_SIZE) { - bp->b_addr = kmem_alloc(size, KM_NOFS); + int align_mask = xfs_buftarg_dma_alignment(bp->b_target); + bp->b_addr = kmem_alloc_io(size, align_mask, KM_NOFS); if (!bp->b_addr) { /* low memory - use alloc_page loop instead */ goto use_alloc_page; @@ -368,7 +369,7 @@ xfs_buf_allocate_memory( } bp->b_offset = offset_in_page(bp->b_addr); bp->b_pages = bp->b_page_array; - bp->b_pages[0] = virt_to_page(bp->b_addr); + bp->b_pages[0] = kmem_to_page(bp->b_addr); bp->b_page_count = 1; bp->b_flags |= _XBF_KMEM; return 0; diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 50d854bfc45c..3e0a105b6cc9 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1403,6 +1403,7 @@ xlog_alloc_log( */ ASSERT(log->l_iclog_size >= 4096); for (i = 0; i < log->l_iclog_bufs; i++) { + int align_mask = xfs_buftarg_dma_alignment(mp->m_logdev_targp); size_t bvec_size = howmany(log->l_iclog_size, PAGE_SIZE) * sizeof(struct bio_vec); @@ -1414,8 +1415,8 @@ xlog_alloc_log( iclog->ic_prev = prev_iclog; prev_iclog = iclog; - iclog->ic_data = kmem_alloc_large(log->l_iclog_size, - KM_MAYFAIL); + iclog->ic_data = kmem_alloc_io(log->l_iclog_size, align_mask, + KM_MAYFAIL); if (!iclog->ic_data) goto out_free_iclog; #ifdef DEBUG diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index eafb36cb4c66..f05c6c99c4f3 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -97,6 +97,8 @@ xlog_alloc_buffer( struct xlog *log, int nbblks) { + int align_mask = xfs_buftarg_dma_alignment(log->l_targ); + /* * Pass log block 0 since we don't have an addr yet, buffer will be * verified on read. @@ -125,7 +127,7 @@ xlog_alloc_buffer( if (nbblks > 1 && log->l_sectBBsize > 1) nbblks += log->l_sectBBsize; nbblks = round_up(nbblks, log->l_sectBBsize); - return kmem_alloc_large(BBTOB(nbblks), KM_MAYFAIL); + return kmem_alloc_io(BBTOB(nbblks), align_mask, KM_MAYFAIL); } /* diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index 8bb8b4704a00..eaae275ed430 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -3604,6 +3604,7 @@ DEFINE_EVENT(xfs_kmem_class, name, \ TP_PROTO(ssize_t size, int flags, unsigned long caller_ip), \ TP_ARGS(size, flags, caller_ip)) DEFINE_KMEM_EVENT(kmem_alloc); +DEFINE_KMEM_EVENT(kmem_alloc_io); DEFINE_KMEM_EVENT(kmem_alloc_large); DEFINE_KMEM_EVENT(kmem_realloc); DEFINE_KMEM_EVENT(kmem_zone_alloc);