diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index cedb83a85dd9..ac0e890510da 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -577,6 +577,9 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 		return host_bridge->align_resource(dev, res,
 				start, size, align);
 
+	if (res->flags & IORESOURCE_MEM)
+		return pci_align_resource(dev, res, empty_res, size, align);
+
 	return start;
 }
 
diff --git a/arch/m68k/kernel/pcibios.c b/arch/m68k/kernel/pcibios.c
index 7e286ee1976b..7a9e60df79c5 100644
--- a/arch/m68k/kernel/pcibios.c
+++ b/arch/m68k/kernel/pcibios.c
@@ -31,11 +31,15 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 				       resource_size_t size,
 				       resource_size_t align)
 {
+	struct pci_dev *dev = data;
 	resource_size_t start = res->start;
 
 	if ((res->flags & IORESOURCE_IO) && (start & 0x300))
 		start = (start + 0x3ff) & ~0x3ff;
 
+	if (res->flags & IORESOURCE_MEM)
+		return pci_align_resource(dev, res, empty_res, size, align);
+
 	return start;
 }
 
diff --git a/arch/mips/pci/pci-generic.c b/arch/mips/pci/pci-generic.c
index aaa1d6de8bef..c2e23d0c1d77 100644
--- a/arch/mips/pci/pci-generic.c
+++ b/arch/mips/pci/pci-generic.c
@@ -38,6 +38,9 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 		return host_bridge->align_resource(dev, res,
 				start, size, align);
 
+	if (res->flags & IORESOURCE_MEM)
+		return pci_align_resource(dev, res, empty_res, size, align);
+
 	return start;
 }
 
diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
index 817e97402afe..dae6dafdd6e0 100644
--- a/arch/mips/pci/pci-legacy.c
+++ b/arch/mips/pci/pci-legacy.c
@@ -70,6 +70,8 @@ pcibios_align_resource(void *data, const struct resource *res,
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
 	} else if (res->flags & IORESOURCE_MEM) {
+		start = pci_align_resource(dev, res, empty_res, size, align);
+
 		/* Make sure we start at our min on all hoses */
 		if (start < PCIBIOS_MIN_MEM + hose->mem_resource->start)
 			start = PCIBIOS_MIN_MEM + hose->mem_resource->start;
diff --git a/arch/parisc/kernel/pci.c b/arch/parisc/kernel/pci.c
index f50be1a63c4c..b8007c7400d4 100644
--- a/arch/parisc/kernel/pci.c
+++ b/arch/parisc/kernel/pci.c
@@ -201,6 +201,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 				       resource_size_t size,
 				       resource_size_t alignment)
 {
+	struct pci_dev *dev = data;
 	resource_size_t align, start = res->start;
 
 	DBG_RES("pcibios_align_resource(%s, (%p) [%lx,%lx]/%x, 0x%lx, 0x%lx)\n",
@@ -212,6 +213,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 	align = (res->flags & IORESOURCE_IO) ? PCIBIOS_MIN_IO : PCIBIOS_MIN_MEM;
 	if (align > alignment)
 		start = ALIGN(start, align);
+	else
+		start = pci_align_resource(dev, res, empty_res, size, alignment);
 
 	return start;
 }
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index e7bfa15da043..8efe95a0c4ff 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1144,6 +1144,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 			return start;
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
+	} else if (res->flags & IORESOURCE_MEM) {
+		start = pci_align_resource(dev, res, empty_res, size, align);
 	}
 
 	return start;
diff --git a/arch/sh/drivers/pci/pci.c b/arch/sh/drivers/pci/pci.c
index 7a0522316ee3..878a27a1acfb 100644
--- a/arch/sh/drivers/pci/pci.c
+++ b/arch/sh/drivers/pci/pci.c
@@ -185,6 +185,8 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 		 */
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
+	} else if (res->flags & IORESOURCE_MEM) {
+		start = pci_align_resource(dev, res, empty_res, size, align);
 	}
 
 	return start;
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 6fbd4b34c3f7..e2de26b82940 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -165,6 +165,8 @@ pcibios_align_resource(void *data, const struct resource *res,
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
 	} else if (res->flags & IORESOURCE_MEM) {
+		start = pci_align_resource(dev, res, empty_res, size, align);
+
 		/* The low 1MB range is reserved for ISA cards */
 		if (start < BIOS_END)
 			start = BIOS_END;
diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c
index 64ccb7e0d92f..305031551136 100644
--- a/arch/xtensa/kernel/pci.c
+++ b/arch/xtensa/kernel/pci.c
@@ -54,6 +54,8 @@ pcibios_align_resource(void *data, const struct resource *res,
 
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
+	} else if (res->flags & IORESOURCE_MEM) {
+		start = pci_align_resource(dev, res, empty_res, size, align);
 	}
 
 	return start;
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index c375e255c509..fbc05cda96ee 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -244,6 +244,41 @@ static int pci_revert_fw_address(struct resource *res, struct pci_dev *dev,
 	return 0;
 }
 
+/*
+ * For mem bridge windows, try to relocate tail remainder space to space
+ * before res->start if there's enough free space there. This enables
+ * tighter packing for resources.
+ */
+resource_size_t pci_align_resource(struct pci_dev *dev,
+				   const struct resource *res,
+				   const struct resource *empty_res,
+				   resource_size_t size,
+				   resource_size_t align)
+{
+	resource_size_t remainder, start_addr;
+
+	if (!(res->flags & IORESOURCE_MEM))
+		return res->start;
+
+	if (IS_ALIGNED(size, align))
+		return res->start;
+
+	remainder = size - ALIGN_DOWN(size, align);
+	/* Don't mess with size that doesn't align with window size granularity */
+	if (!IS_ALIGNED(remainder, pci_min_window_alignment(dev->bus, res->flags)))
+		return res->start;
+	/* Try to place remainder that doesn't fill align before */
+	if (res->start < remainder)
+		return res->start;
+	start_addr = res->start - remainder;
+	if (empty_res->start > start_addr)
+		return res->start;
+
+	pci_dbg(dev, "%pR: moving candidate start address below align to %llx\n",
+		res, (unsigned long long)start_addr);
+	return start_addr;
+}
+
 /*
  * We don't have to worry about legacy ISA devices, so nothing to do here.
  * This is marked as __weak because multiple architectures define it; it should
@@ -255,7 +290,9 @@ resource_size_t __weak pcibios_align_resource(void *data,
 					      resource_size_t size,
 					      resource_size_t align)
 {
-	return res->start;
+	struct pci_dev *dev = data;
+
+	return pci_align_resource(dev, res, empty_res, size, align);
 }
 
 static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ac332ff9da9f..cedf948dc614 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1210,6 +1210,11 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 				       const struct resource *empty_res,
 				       resource_size_t size,
 				       resource_size_t align);
+resource_size_t pci_align_resource(struct pci_dev *dev,
+				   const struct resource *res,
+				   const struct resource *empty_res,
+				   resource_size_t size,
+				   resource_size_t align);
 
 /* Generic PCI functions used internally */
 
diff --git a/kernel/resource.c b/kernel/resource.c
index 8c5fcb30fc33..d02a53fb95d8 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -766,7 +766,7 @@ static int __find_resource_space(struct resource *root, struct resource *old,
 			}
 			alloc.end = alloc.start + size - 1;
 			if (alloc.start <= alloc.end &&
-			    __resource_contains_unbound(&avail, &alloc)) {
+			    __resource_contains_unbound(&full_avail, &alloc)) {
 				new->start = alloc.start;
 				new->end = alloc.end;
 				return 0;